Ectonucleotidase inhibitors and methods of use thereof

ABSTRACT

The invention relates to novel heterocyclic compounds and pharmaceutical preparations thereof. The invention further relates to methods of treating or preventing cancer using the novel heterocyclic compounds of the invention.

RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No. 16/447,159 filed Jun. 20, 2019, which claims the benefit of U.S. Provisional Application No. 62/688,225, filed Jun. 21, 2018, and U.S. Provisional Application No. 62/827,505, filed Apr. 1, 2019, each of which is hereby incorporated by reference in its entirety.

BACKGROUND

CD73, also referred to as 5′-nucleotidase (5′-NT) or ecto-5′-nucleotidase (Ecto 5′NTase), is a membrane-bound cell surface enzyme whose primary role is to catalyze the conversion of extracellular nucleotides (e.g., AMP) to their corresponding nucleosides (e.g., adenosine). CD73 is found in most tissues and expressed on lymphocytes, endothelial cells, and epithelial cells. It is also widely expressed in many tumor cell lines and, notably, is upregulated in cancerous tissues (Antonioli et al., Nat. Rev. Cancer, 13: 842-857, 2013).

In tandem with CD39 (ecto-ATPase), CD73 generates adenosine from ATP/AMP, which is often released from damaged or inflamed cells into the extracellular environment. Extracellular adenosine produced by CD73 interacts with G-protein coupled receptors on target cells. An important downstream effect of this signaling is increased immunosuppression via a number of pathways. For example, CD73 is a co-signaling molecule on T lymphocytes. Under normal circumstances, extracellular adenosine levels promote a self-limiting immune response that prevents excessive inflammation and tissue damage. For tumors, an advantage of abnormally increased CD73 is that the resulting increased CD73-catalyzed adenosine levels yield inhibition of anti-tumor immune system responses.

Even though CD73 plays a role in cancer immunosuppression, higher expression of CD73 is associated with a variety of stages of tumor progression, including tumor vascularization, invasiveness, and metastasis, and with shorter breast cancer patient survival time. Some of these observations result from CD73's enzyme-independent function as an adhesion molecule required for lymphocyte binding to the endothelium.

Overall, CD73 has become an important target for developing new cancer therapies, either as single agents or in combination with other cancer therapies. Indeed, combining CD73 monoclonal antibodies with antibodies for other chemotherapy targets enhances response and survival in animal cancer models (Allard et al., Clin. Cancer Res., 19:5626-35, 2013).

Many of the current cancer treatments and chemotherapeutic agents fail to successfully treat all patients or all symptoms in treated patients, and many of these therapies are associated with undesirable side effects. As certain cancers develop resistance to various chemotherapeutic agents, alternate cancer therapies are needed. Thus, there is a need for additional compounds and methods for treating cancer and other diseases.

SUMMARY

Disclosed herein are compounds of Formula (I):

or a pharmaceutically acceptable salt and/or prodrug thereof, wherein

-   -   Y is

-   -   Het is heterocyclyl or heteroaryl;     -   R^(1a) is selected from H, halo, hydroxy, cyano, azido, amino,         C₁₋₆alkyl, hydroxyC₁₋₆alkyl, amino-C₁₋₆alkyl,         —O—C(O)—O—C₁₋₆alkyl, C₁₋₆acyloxy, C₁₋₆alkoxy, C₂₋₆alkenyl, and         C₂₋₆alkynyl;     -   R^(1b) is selected from H, halo, C₁₋₆alkyl, hydroxy-C₁₋₆alkyl,         amino-C₁₋₆alkyl, C₂₋₆alkenyl, and C₂₋₆alkynyl;     -   R^(2a) is selected from halo, hydroxy, cyano, azido, amino,         C₁₋₆alkyl, hydroxy-C₁₋₆alkyl, amino-C₁₋₆alkyl, C₁₋₆acyloxy,         —O—C(O)—O—C₁₋₆alkyl, C₁₋₆alkoxy, C₂₋₆alkenyl, and C₂₋₆alkynyl;     -   R^(2b) is selected from halo, C₁₋₆alkyl, C₂₋₆alkenyl, and         C₂₋₆alkynyl, preferably substituted or unsubstituted C₂alkynyl,         most preferably unsubstituted C₂alkynyl;     -   R³ is selected from H and alkyl;     -   R⁴ is selected from H, alkyl, CN, aryl, heteroaryl, —C(O)OR⁹,         —C(O)NR¹¹R¹², —S(O)₂R¹⁰, —P(O)(OR¹¹)(OR¹²), and         —P(O)(OR¹¹)(NR¹³R¹⁴);     -   R⁵ is selected from H, cyano, alkyl, cycloalkylalkyl,         heterocyclylalkyl, aralkyl, heteroaralkyl, and —C(O)OR⁹;     -   R⁶ is selected from —C(O)OR⁹, —C(O)NR¹⁶R¹⁷, and         —P(O)(OR¹¹)(OR¹²);     -   R⁹ is independently selected from H, alkyl, cycloalkyl,         cycloalkylalkyl, heterocyclyl, heterocyclylalkyl, aryl, aralkyl,         heteroaryl, and heteroaralkyl;     -   R¹⁰ is independently selected from alkyl, alkenyl, alkynyl,         amino, cycloalkyl, cycloalkylalkyl, heterocyclyl,         heterocyclylalkyl, aryl, aralkyl, heteroaryl, and heteroaralkyl;         and     -   each R¹¹ and R¹² is independently selected from H, alkyl,         cycloalkyl, cycloalkylalkyl, heterocyclyl, heterocyclylalkyl,         aryl, aralkyl, heteroaryl, heteroaralkyl; or     -   R¹¹ and R¹², together with the nitrogen atom to which they are         attached, form a 5- to 7-membered heterocyclyl;     -   R¹³ is H or alkyl;     -   R¹⁴ is alkyl or aralkyl;     -   each R¹⁵ is independently selected from hydroxy, alkoxy acyloxy         and NR¹³R¹⁴;     -   each R¹⁶ and R¹⁷ is independently selected from H, hydroxy,         alkyl, cycloalkyl, cycloalkylalkyl, heterocyclyl,         heterocyclylalkyl, aryl, aralkyl, heteroaryl, heteroaralkyl; or     -   R¹⁶ and R¹⁷, together with the nitrogen atom to which they are         attached, form a 5- to 7-membered heterocyclyl.     -   In certain preferred embodiments of Formula I, the included         compounds meet the terms of a) and b); or a) and c);

wherein:

-   -   a) the compound is not

-   -   b) if R⁴ and R⁶ are each —C(O)OH and R⁵ is benzyl substituted on         the phenyl ring with a heterocyclyl or heteroaryl substituent,         then the phenyl ring substituent is selected from unsubstituted         or substituted pyrrolidinyl, piperazinonyl, piperidonyl,         tetrahydropyrimidonyl, pyridonyl, and pyridyl; and     -   c) if R⁴ is —C(O)OH or tetrazolyl, R⁶ is —C(O)OH, and R⁵ is         benzyl substituted on the phenyl ring with a second phenyl ring,         then either the benzyl phenyl ring or the second phenyl ring is         substituted with —C(O)OR⁹ where R⁹ is H or alkyl.

In some embodiments, Y is

In other embodiments, Y is

In certain preferred embodiments:

-   -   a) the compound is not

and

-   -   b) R_(2b) is selected from halo, C₂₋₆alkyl, C₂₋₆alkenyl, and         C₂₋₆alkynyl, preferably substituted or unsubstituted C₂alkynyl,         most preferably unsubstituted C₂alkynyl; and either     -   c) R⁵ is benzyl substituted on the phenyl ring with a         substituent selected from unsubstituted or substituted         piperidonyl, tetrahydropyrimidonyl, pyridonyl, and pyridyl, or     -   d) R⁵ is benzyl substituted on the phenyl ring with a second         phenyl ring substituted with —C(O)OR⁹ where R⁹ is H or alkyl.

In certain embodiments, the present invention provides a pharmaceutical composition suitable for use in a subject in the treatment or prevention of cancer comprising an effective amount of any of the compounds described herein (e.g., a compound of the invention, such as a compound of Formula (I), or a pharmaceutically acceptable salt thereof, and one or more pharmaceutically acceptable excipients. In certain embodiments, the pharmaceutical preparations may be for use in treating or preventing a condition or disease as described herein.

Disclosed herein are methods of treating diseases and conditions that benefit from the inhibition of CD73, comprising administering to a subject in need thereof an effective amount of a compound as disclosed herein (e.g., a compound of Formula (I) or any of the embodiments thereof disclosed herein). In certain embodiments, the human subject is in need of such treatment. These diseases include, but are not limited to cancers, such as lung cancer, kidney cancer, skin cancer, breast cancer, and ovarian cancer. Other diseases and conditions that can be treated using the methods described herein include, but are not limited to, neurological, neurodegenerative and CNS disorders and diseases such as depression and Parkinson's disease, cerebral and cardiac ischemic diseases, sleep disorders, fibrosis, immune and inflammatory disorders.

Provided herein are combination therapies of compounds of formula (I) with monoclonal antibodies and other chemotherapeutic agents that can enhance the therapeutic benefit beyond the ability of the adjuvant therapy alone.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1A depicts the increase in % CD8+ cells of CD45+ cells in EG7 tumors from mice treated with Compound 9.

FIG. 1B depicts the reversal of efficacy using Compound 9 when CD8+ cells are depleted with an anti-CD8 antibody.

FIG. 2A depicts the reversal of AMP-mediated suppression of CD8+ T cells using the CD73 inhibitor Compound 9, including the EC₅₀=11.6 nM for CD8+ T cell proliferation.

FIG. 2B depicts the EC₅₀=9.6 nM for CD8+ T cell activation.

FIG. 2C depicts the EC₅₀=4.5 nM for IFN-gamma production.

FIG. 2D depicts the EC₅₀=5.6 nM for Granzyme B production.

FIG. 3A depicts the effect of Compound 9 on proliferation of certain cell lines, including the comparable % cell survival of EG7 cells, a mouse T cell lymphoma cell line.

FIG. 3B depicts the comparable % cell survival of A375 cells, a human melanoma cell line.

FIG. 3C depicts the comparable % divided cells of human CD8+ T cells.

FIG. 4A depicts the potency of Compound 9 as evaluated against CD73 and CD73-expressing SK-MEL-28 cells.

FIG. 4B depicts the IC₅₀=0.17 nM for human recombinant CD73.

FIG. 4C depicts the IC₅₀=0.38 nM for human plasma CD73.

FIG. 4D depicts the IC₅₀=0.21 nM for human CD73 cell surface assay.

FIG. 5A depicts the level of Compound 9 in mouse plasma.

FIG. 5B depicts the inhibition of CD73 in mouse plasma.

FIG. 6A depicts the efficacy of Compound 9 against EG7 tumors.

FIG. 6B depicts the efficacy of Compound 9 against CT26 tumors.

FIG. 7A depicts the reduction in tumor volume with single agent Compound 9 and combination therapy with anti-PD-L1 antibody.

FIGS. 7B-7E show individual replications of this measurement for each dosing. FIG. 7B is vehicle. FIG. 7C is anti-PD-L1 antibody. FIG. 7D is Compound 9. FIG. 7E is Compound 9+Anti-PD-L1.

FIG. 8A depicts the reduction in tumor volume with single agent Compound 9 and combination therapy with oxaliplatin.

FIGS. 8B-8E show individual replications of this measurement for each dosing. FIG. 8B is vehicle. FIG. 8C is oxaliplatin. FIG. 8D is Compound 9. FIG. 8E is Compound 9+oxaliplatin.

FIG. 9A depicts the reduction in tumor volume with single agent Compound 9 and combination therapy with doxorubicin.

FIGS. 9B-9E show individual replications of this measurement for each dosing. FIG. 9B is vehicle. FIG. 9C is doxorubicin. FIG. 9D is Compound 9. FIG. 9E is Compound 9+doxorubicin.

FIG. 10A depicts the sub-nanomolar inhibition of CD73 activity in head and neck squamous cell carcinoma (HNSCC) serum by Compound 9.

FIG. 10B depicts the sub-nanomolar inhibition of CD73 activity in ovarian cancer serum by Compound 9.

FIG. 10C depicts the sub-nanomolar inhibition of CD73 activity in triple-negative breast cancer (TNBC) serum by compound 9.

FIG. 10D depicts the sub-nanomolar inhibition of CD73 activity in esophageal cancer serum by Compound 9.

FIG. 11 depicts normalized mRNA expression levels of CD73 in tumor and normal tissues.

FIG. 12A depicts the reduction in tumor volume with single agent Compound 9 and combination therapy with docetaxel in EG7 tumor model.

FIGS. 12B-12E depict individual replications of the reduction in tumor volume.

FIG. 12B shows vehicle. FIG. 12C is Compound 9. FIG. 12D is docetaxel. FIG. 12E is Compound 9+docetaxel.

FIG. 13A depicts Compound 9 reduced the growth of established EG7 tumors.

FIGS. 13B-13D depict individual replications of the reduction in tumor growth.

FIG. 13B is vehicle. FIG. 13C is dosing of Compound 9 started on day 1. FIG. 13D is Compound 9 started on day 6.

DETAILED DESCRIPTION Definitions

Unless defined otherwise, all technical and scientific terms used herein have the meaning commonly understood by a person skilled in the art of the present disclosure. The following references provide one of skill with a general definition of many of the terms used in this disclosure: Singleton et al., Dictionary of Microbiology and Molecular Biology (2nd ed. 1994); The Cambridge Dictionary of Science and Technology (Walker ed., 1988); The Glossary of Genetics, 5th Ed., R. Rieger et al. (eds.), Springer Verlag (1991); and Hale & Marham, The Harper Collins Dictionary of Biology (1991). As used herein, the following terms have the meanings ascribed to them below, unless specified otherwise.

In some embodiments, chemical structures are disclosed with a corresponding chemical name. In case of conflict, the chemical structure controls the meaning, rather than the name.

In this disclosure, “comprises,” “comprising,” “containing” and “having” and the like can have the meaning ascribed to them in U.S. Patent law and can mean “includes,” “including,” and the like; “consisting essentially of” or “consists essentially” likewise has the meaning ascribed in U.S. Patent law and the term is open-ended, allowing for the presence of more than that which is recited so long as basic or novel characteristics of that which is recited are not substantially changed by the presence of more than that which is recited, but excludes prior art embodiments.

Unless specifically stated or obvious from context, as used herein, the term “or” is understood to be inclusive. Unless specifically stated or obvious from context otherwise, as used herein, the terms “a”, “an”, and “the” are understood to be singular or plural.

The term “acyl” is art-recognized and refers to a group represented by the general formula hydrocarbylC(O)—, preferably alkylC(O)—.

The term “acylamino” is art-recognized and refers to an amino group substituted with an acyl group and may be represented, for example, by the formula hydrocarbylC(O)NH—.

The term “acyloxy” is art-recognized and refers to a group represented by the general formula hydrocarbylC(O)O—, preferably alkylC(O)O—.

The term “alkoxy” refers to an alkyl group, preferably a lower alkyl group, having an oxygen attached thereto. Representative alkoxy groups include methoxy, ethoxy, propoxy, tert-butoxy and the like.

The term “alkoxyalkyl” refers to an alkyl group substituted with an alkoxy group and may be represented by the general formula alkyl-O-alkyl.

The term “alkenyl”, as used herein, refers to an aliphatic group containing at least one double bond and is intended to include both “unsubstituted alkenyls” and “substituted alkenyls”, the latter of which refers to alkenyl moieties having substituents replacing a hydrogen on one or more carbons of the alkenyl group. Such substituents may occur on one or more carbons that are included or not included in one or more double bonds. Moreover, such substituents include all those contemplated for alkyl groups, as discussed below, except where stability is prohibitive. For example, substitution of alkenyl groups by one or more alkyl, carbocyclyl, aryl, heterocyclyl, or heteroaryl groups is contemplated.

An “alkyl” group or “alkane” is a straight chained or branched non-aromatic hydrocarbon which is completely saturated. Typically, a straight chained or branched alkyl group has from 1 to about 20 carbon atoms, preferably from 1 to about 10 unless otherwise defined. Examples of straight chained and branched alkyl groups include methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl, tert-butyl, pentyl, hexyl, pentyl and octyl. A C₁-C₆ straight chained or branched alkyl group is also referred to as a “lower alkyl” group.

Moreover, the term “alkyl” (or “lower alkyl”) as used throughout the specification, examples, and claims is intended to include both “unsubstituted alkyls” and “substituted alkyls”, the latter of which refers to alkyl moieties having substituents replacing a hydrogen on one or more carbons of the hydrocarbon backbone. Such substituents, if not otherwise specified, can include, for example, a halogen, a hydroxyl, a carbonyl (such as a carboxyl, an alkoxycarbonyl, a formyl, or an acyl), a thiocarbonyl (such as a thioester, a thioacetate, or a thioformate), an alkoxy, a phosphoryl, a phosphate, a phosphonate, a phosphinate, an amino, an amido, an amidine, an imine, a cyano, a nitro, an azido, a sulfhydryl, an alkylthio, a sulfate, a sulfonate, a sulfamoyl, a sulfonamido, a sulfonyl, a heterocyclyl, an aralkyl, or an aromatic or heteroaromatic moiety. It will be understood by those skilled in the art that the moieties substituted on the hydrocarbon chain can themselves be substituted, if appropriate. For instance, the substituents of a substituted alkyl may include substituted and unsubstituted forms of amino, azido, imino, amido, phosphoryl (including phosphonate and phosphinate), sulfonyl (including sulfate, sulfonamido, sulfamoyl and sulfonate), and silyl groups, as well as ethers, alkylthios, carbonyls (including ketones, aldehydes, carboxylates, and esters), —CF₃, —CN and the like. Exemplary substituted alkyls are described below. Cycloalkyls can be further substituted with alkyls, alkenyls, alkoxys, alkylthios, aminoalkyls, carbonyl-substituted alkyls, —CF₃, —CN, and the like.

The term “C_(x-y)” when used in conjunction with a chemical moiety, such as, acyl, acyloxy, alkyl, alkenyl, alkynyl, or alkoxy is meant to include groups that contain from x to y carbons in the chain. For example, the term “C_(x-y)alkyl” refers to substituted or unsubstituted saturated hydrocarbon groups, including straight-chain alkyl and branched-chain alkyl groups that contain from x to y carbons in the chain, including haloalkyl groups such as trifluoromethyl and 2,2,2-tirfluoroethyl, etc. C₀ alkyl indicates a hydrogen where the group is in a terminal position, a bond if internal. The terms “C_(2-y)alkenyl” and “C_(2-y)alkynyl” refer to substituted or unsubstituted unsaturated aliphatic groups analogous in length and possible substitution to the alkyls described above, but that contain at least one double or triple bond respectively.

The term “alkylamino”, as used herein, refers to an amino group substituted with at least one alkyl group.

The term “alkylthio”, as used herein, refers to a thiol group substituted with an alkyl group and may be represented by the general formula alkylS—.

The term “alkynyl”, as used herein, refers to an aliphatic group containing at least one triple bond and is intended to include both “unsubstituted alkynyls” and “substituted alkynyls”, the latter of which refers to alkynyl moieties having substituents replacing a hydrogen on one or more carbons of the alkynyl group. Such substituents may occur on one or more carbons that are included or not included in one or more triple bonds. Moreover, such substituents include all those contemplated for alkyl groups, as discussed above, except where stability is prohibitive. For example, substitution of alkynyl groups by one or more alkyl, carbocyclyl, aryl, heterocyclyl, or heteroaryl groups is contemplated.

The term “amide”, as used herein, refers to a group

wherein each R³⁰ independently represents a hydrogen or hydrocarbyl group, or two R³⁰ are taken together with the N atom to which they are attached complete a heterocycle having from 4 to 8 atoms in the ring structure.

The terms “amine” and “amino” are art-recognized and refer to both unsubstituted and substituted amines and salts thereof, e.g., a moiety that can be represented by

wherein each R³¹ independently represents a hydrogen or a hydrocarbyl group, or two R₃₁ are taken together with the N atom to which they are attached complete a heterocycle having from 4 to 8 atoms in the ring structure. The term “aminoalkyl”, as used herein, refers to an alkyl group substituted with an amino group.

The term “aralkyl”, as used herein, refers to an alkyl group substituted with an aryl group.

The term “aryl” as used herein include substituted or unsubstituted single-ring aromatic groups in which each atom of the ring is carbon. Preferably, the ring is a 5- to 7-membered ring, more preferably a 6-membered ring. The term “aryl” also includes polycyclic ring systems having two or more cyclic rings in which two or more carbons are common to two adjoining rings wherein at least one of the rings is aromatic, e.g., the other cyclic rings can be cycloalkyls, cycloalkenyls, cycloalkynyls, aryls, heteroaryls, and/or heterocyclyls. Aryl groups include benzene, naphthalene, phenanthrene, phenol, aniline, and the like.

The term “carbamate” is art-recognized and refers to a group

wherein R³² and R³³ independently represent hydrogen or a hydrocarbyl group, such as an alkyl group, or R³² and R³³ taken together with the intervening atom(s) complete a heterocycle having from 4 to 8 atoms in the ring structure.

The terms “carbocycle”, and “carbocyclic”, as used herein, refers to a saturated or unsaturated ring in which each atom of the ring is carbon. The term carbocycle includes both aromatic carbocycles and non-aromatic carbocycles. Non-aromatic carbocycles include both cycloalkane rings, in which all carbon atoms are saturated, and cycloalkene rings, which contain at least one double bond.

The term “carbocycle” includes 5-7 membered monocyclic and 8-12 membered bicyclic rings. Each ring of a bicyclic carbocycle may be selected from saturated, unsaturated and aromatic rings. Carbocycle includes bicyclic molecules in which one, two or three or more atoms are shared between the two rings. The term “fused carbocycle” refers to a bicyclic carbocycle in which each of the rings shares two adjacent atoms with the other ring. Each ring of a fused carbocycle may be selected from saturated, unsaturated and aromatic rings. In an exemplary embodiment, an aromatic ring, e.g., phenyl, may be fused to a saturated or unsaturated ring, e.g., cyclohexane, cyclopentane, or cyclohexene. Any combination of saturated, unsaturated and aromatic bicyclic rings, as valence permits, is included in the definition of carbocyclic. Exemplary “carbocycles” include cyclopentane, cyclohexane, bicyclo[2.2.1]heptane, 1,5-cyclooctadiene, 1,2,3,4-tetrahydronaphthalene, bicyclo[4.2.0]oct-3-ene, naphthalene and adamantane. Exemplary fused carbocycles include decalin, naphthalene, 1,2,3,4-tetrahydronaphthalene, bicyclo[4.2.0]octane, 4,5,6,7-tetrahydro-1H-indene and bicyclo[4.1.0]hept-3-ene. “Carbocycles” may be substituted at any one or more positions capable of bearing a hydrogen atom.

A “cycloalkyl” group is a cyclic hydrocarbon which is completely saturated. “Cycloalkyl” includes monocyclic and bicyclic rings. Typically, a monocyclic cycloalkyl group has from 3 to about 10 carbon atoms, more typically 3 to 8 carbon atoms unless otherwise defined. The second ring of a bicyclic cycloalkyl may be selected from saturated, unsaturated and aromatic rings. Cycloalkyl includes bicyclic molecules in which one, two or three or more atoms are shared between the two rings. The term “fused cycloalkyl” refers to a bicyclic cycloalkyl in which each of the rings shares two adjacent atoms with the other ring. The second ring of a fused bicyclic cycloalkyl may be selected from saturated, unsaturated and aromatic rings. A “cycloalkenyl” group is a cyclic hydrocarbon containing one or more double bonds.

The term “carbocyclylalkyl”, as used herein, refers to an alkyl group substituted with a carbocycle group.

The term “carbonate” is art-recognized and refers to a group —OCO₂—R³⁴, wherein R³⁴ represents a hydrocarbyl group.

The term “carboxy”, as used herein, refers to a group represented by the formula —CO₂H.

The term “ester”, as used herein, refers to a group —C(O)OR³⁵ wherein R³⁵ represents a hydrocarbyl group.

The term “ether”, as used herein, refers to a hydrocarbyl group linked through an oxygen to another hydrocarbyl group. Accordingly, an ether substituent of a hydrocarbyl group may be hydrocarbyl-O—. Ethers may be either symmetrical or unsymmetrical. Examples of ethers include, but are not limited to, heterocycle-O-heterocycle and aryl-O-heterocycle. Ethers include “alkoxyalkyl” groups, which may be represented by the general formula alkyl-O-alkyl.

The terms “halo” and “halogen” as used herein means halogen and includes chloro, fluoro, bromo, and iodo.

The terms “hetaralkyl” and “heteroaralkyl”, as used herein, refers to an alkyl group substituted with a hetaryl group.

The term “heteroalkyl”, as used herein, refers to a saturated or unsaturated chain of carbon atoms and at least one heteroatom, wherein no two heteroatoms are adjacent.

The terms “heteroaryl” and “hetaryl” include substituted or unsubstituted aromatic single ring structures, preferably 5- to 7-membered rings, more preferably 5- to 6-membered rings, whose ring structures include at least one heteroatom, preferably one to four heteroatoms, more preferably one or two heteroatoms. The terms “heteroaryl” and “hetaryl” also include polycyclic ring systems having two or more cyclic rings in which two or more carbons are common to two adjoining rings wherein at least one of the rings is heteroaromatic, e.g., the other cyclic rings can be cycloalkyls, cycloalkenyls, cycloalkynyls, aryls, heteroaryls, and/or heterocyclyls. Heteroaryl groups include, for example, pyrrole, furan, thiophene, imidazole, oxazole, thiazole, pyrazole, pyridine, pyrazine, pyridazine, and pyrimidine, and the like.

The term “heteroatom” as used herein means an atom of any element other than carbon or hydrogen. Preferred heteroatoms are nitrogen, oxygen, and sulfur.

The terms “heterocyclyl”, “heterocycle”, and “heterocyclic” refer to substituted or unsubstituted non-aromatic ring structures, preferably 3- to 10-membered rings, more preferably 3- to 7-membered rings, whose ring structures include at least one heteroatom, preferably one to four heteroatoms, more preferably one or two heteroatoms. The terms “heterocyclyl” and “heterocyclic” also include polycyclic ring systems having two or more cyclic rings in which two or more carbons are common to two adjoining rings wherein at least one of the rings is heterocyclic, e.g., the other cyclic rings can be cycloalkyls, cycloalkenyls, cycloalkynyls, aryls, heteroaryls, and/or heterocyclyls. Heterocyclyl groups include, for example, piperidine, piperazine, pyrrolidine, morpholine, lactones, lactams, and the like.

The term “heterocyclylalkyl”, as used herein, refers to an alkyl group substituted with a heterocycle group.

The term “hydrocarbyl”, as used herein, refers to a group that is bonded through a carbon atom that does not have a ═O or ═S substituent, and typically has at least one carbon-hydrogen bond and a primarily carbon backbone, but may optionally include heteroatoms.

Thus, groups like methyl, ethoxyethyl, 2-pyridyl, and trifluoromethyl are considered to be hydrocarbyl for the purposes of this application, but substituents such as acetyl (which has a ═O substituent on the linking carbon) and ethoxy (which is linked through oxygen, not carbon) are not. Hydrocarbyl groups include, but are not limited to aryl, heteroaryl, carbocycle, heterocyclyl, alkyl, alkenyl, alkynyl, and combinations thereof.

The term “hydroxyalkyl”, as used herein, refers to an alkyl group substituted with a hydroxy group.

The term “lower” when used in conjunction with a chemical moiety, such as, acyl, acyloxy, alkyl, alkenyl, alkynyl, or alkoxy is meant to include groups where there are ten or fewer non-hydrogen atoms in the substituent, preferably six or fewer. A “lower alkyl”, for example, refers to an alkyl group that contains ten or fewer carbon atoms, preferably six or fewer. In certain embodiments, acyl, acyloxy, alkyl, alkenyl, alkynyl, or alkoxy substituents defined herein are respectively lower acyl, lower acyloxy, lower alkyl, lower alkenyl, lower alkynyl, or lower alkoxy, whether they appear alone or in combination with other substituents, such as in the recitations hydroxyalkyl and aralkyl (in which case, for example, the atoms within the aryl group are not counted when counting the carbon atoms in the alkyl substituent).

The terms “polycyclyl”, “polycycle”, and “polycyclic” refer to two or more rings (e.g., cycloalkyls, cycloalkenyls, cycloalkynyls, aryls, heteroaryls, and/or heterocyclyls) in which two or more atoms are common to two adjoining rings, e.g., the rings are “fused rings”. Each of the rings of the polycycle can be substituted or unsubstituted. In certain embodiments, each ring of the polycycle contains from 3 to 10 atoms in the ring, preferably from 5 to 7.

The term “silyl” refers to a silicon moiety with three hydrocarbyl moieties attached thereto.

The term “substituted” refers to moieties having substituents replacing a hydrogen on one or more carbons of the backbone. It will be understood that “substitution” or “substituted with” includes the implicit proviso that such substitution is in accordance with permitted valence of the substituted atom and the substituent, and that the substitution results in a stable compound, e.g., which does not spontaneously undergo transformation such as by rearrangement, cyclization, elimination, etc. As used herein, the term “substituted” is contemplated to include all permissible substituents of organic compounds. In a broad aspect, the permissible substituents include acyclic and cyclic, branched and unbranched, carbocyclic and heterocyclic, aromatic and non-aromatic substituents of organic compounds. The permissible substituents can be one or more and the same or different for appropriate organic compounds. For purposes of this invention, the heteroatoms such as nitrogen may have hydrogen substituents and/or any permissible substituents of organic compounds described herein which satisfy the valences of the heteroatoms. Substituents can include any substituents described herein, for example, a halogen, a hydroxyl, a carbonyl (such as a carboxyl, an alkoxycarbonyl, a formyl, or an acyl), a thiocarbonyl (such as a thioester, a thioacetate, or a thioformate), an alkoxy, a phosphoryl, a phosphate, a phosphonate, a phosphinate, an amino, an amido, an amidine, an imine, a cyano, a nitro, an azido, a sulfhydryl, an alkylthio, a sulfate, a sulfonate, a sulfamoyl, a sulfonamido, a sulfonyl, a heterocyclyl, an aralkyl, or an aromatic or heteroaromatic moiety. It will be understood by those skilled in the art that substituents can themselves be substituted, if appropriate. Unless specifically stated as “unsubstituted,” references to chemical moieties herein are understood to include substituted variants. For example, reference to an “aryl” group or moiety implicitly includes both substituted and unsubstituted variants.

The term “sulfate” is art-recognized and refers to the group —OSO₃H, or a pharmaceutically acceptable salt thereof.

The term “sulfonamide” is art-recognized and refers to the group represented by the general formulae

wherein R³⁶ and R³⁷ independently represent hydrogen or hydrocarbyl, such as alkyl, or R³⁶ and R³⁷ taken together with the intervening atom(s) complete a heterocycle having from 4 to 8 atoms in the ring structure.

The term “sulfoxide” is art-recognized and refers to the group —S(O)—R³⁸, wherein R³⁸ represents a hydrocarbyl.

The term “sulfonate” is art-recognized and refers to the group SO₃H, or a pharmaceutically acceptable salt thereof.

The term “sulfone” is art-recognized and refers to the group —S(O)₂—R³⁹, wherein R³⁹ represents a hydrocarbyl.

The term “thioalkyl”, as used herein, refers to an alkyl group substituted with a thiol group.

The term “thioester”, as used herein, refers to a group —C(O)SR⁴⁰ or —SC(O)R⁴⁰ wherein R¹⁰ represents a hydrocarbyl.

The term “thioether”, as used herein, is equivalent to an ether, wherein the oxygen is replaced with a sulfur.

The term “urea” is art-recognized and may be represented by the general formula

wherein R⁴¹ and R⁴² independently represent hydrogen or a hydrocarbyl, such as alkyl, or either occurrence of R⁴¹ taken together with R⁴² and the intervening atom(s) complete a heterocycle having from 4 to 8 atoms in the ring structure.

The term “protecting group” refers to a group of atoms that, when attached to a reactive functional group in a molecule, mask, reduce or prevent the reactivity of the functional group. Typically, a protecting group may be selectively removed as desired during the course of a synthesis. Examples of protecting groups can be found in Greene and Wuts, Protective Groups in Organic Chemistry, 3^(rd) Ed., 1999, John Wiley & Sons, NY and Harrison et al., Compendium of Synthetic Organic Methods, Vols. 1-8, 1971-1996, John Wiley & Sons, NY. Representative nitrogen protecting groups include, but are not limited to, formyl, acetyl, trifluoroacetyl, benzyl, benzyloxycarbonyl (“CBZ”), tert-butoxycarbonyl (“Boc”), trimethylsilyl (“TMS”), 2-trimethylsilyl-ethanesulfonyl (“TES”), trityl and substituted trityl groups, allyloxycarbonyl, 9-fluorenylmethyloxycarbonyl (“FMOC”), nitro-veratryloxycarbonyl (“NVOC”) and the like. Representative hydroxyl protecting groups include, but are not limited to, those where the hydroxyl group is either acylated (esterified) or alkylated such as benzyl and trityl ethers, as well as alkyl ethers, tetrahydropyranyl ethers, trialkylsilyl ethers (e.g., TMS or TIPS groups), glycol ethers, such as ethylene glycol and propylene glycol derivatives and allyl ethers.

In certain embodiments, compounds of the invention may be racemic. In certain embodiments, compounds of the invention may be enriched in one enantiomer. For example, a compound of the invention may have greater than about 30% ee, about 40% ee, about 50% ee, about 60% ee, about 70% ee, about 80% ee, about 90% ee, or even about 95% or greater ee. In certain embodiments, compounds of the invention may have more than one stereocenter. In certain such embodiments, compounds of the invention may be enriched in one or more diastereomer. For example, a compound of the invention may have greater than about 30% de, about 40% de, about 50% de, about 60% de, about 70% de, about 80% de, about 90% de, or even about 95% or greater de.

In certain embodiments, the therapeutic preparation may be enriched to provide predominantly one enantiomer of a compound (e.g., of Formula (I)). An enantiomerically enriched mixture may comprise, for example, at least about 60 mol percent of one enantiomer, or more preferably at least about 75, about 90, about 95, or even about 99 mol percent. In certain embodiments, the compound enriched in one enantiomer is substantially free of the other enantiomer, wherein substantially free means that the substance in question makes up less than about 10%, or less than about 5%, or less than about 4%, or less than about 3%, or less than about 2%, or less than about 1% as compared to the amount of the other enantiomer, e.g., in the composition or compound mixture. For example, if a composition or compound mixture contains about 98 grams of a first enantiomer and about 2 grams of a second enantiomer, it would be said to contain about 98 mol percent of the first enantiomer and only about 2% of the second enantiomer.

In certain embodiments, the therapeutic preparation may be enriched to provide predominantly one diastereomer of a compound (e.g., of Formula (I)). A diastereomerically enriched mixture may comprise, for example, at least about 60 mol percent of one diastereomer, or more preferably at least about 75, about 90, about 95, or even about 99 mol percent.

The term “subject” to which administration is contemplated includes, but is not limited to, humans (i.e., a male or female of any age group, e.g., a pediatric subject (e.g., infant, child, adolescent) or adult subject (e.g., young adult, middle-aged adult or senior adult)) and/or other primates (e.g., cynomolgus monkeys, rhesus monkeys); mammals, including commercially relevant mammals such as cattle, pigs, horses, sheep, goats, cats, and/or dogs; and/or birds, including commercially relevant birds such as chickens, ducks, geese, quail, and/or turkeys. Preferred subjects are humans.

As used herein, a therapeutic that “prevents” a disorder or condition refers to a compound that, in a statistical sample, reduces the occurrence of the disorder or condition in the treated sample relative to an untreated control sample, or delays the onset or reduces the severity of one or more symptoms of the disorder or condition relative to the untreated control sample.

The term “treating” includes prophylactic and/or therapeutic treatments. The term “prophylactic or therapeutic” treatment is art-recognized and includes administration to the subject of one or more of the disclosed compositions. If it is administered prior to clinical manifestation of the unwanted condition (e.g., disease or other unwanted state of the subject) then the treatment is prophylactic (i.e., it protects the subject against developing the unwanted condition), whereas if it is administered after manifestation of the unwanted condition, the treatment is therapeutic, (i.e., it is intended to diminish, ameliorate, or stabilize the existing unwanted condition or side effects thereof).

The term “prodrug” is intended to encompass compounds which, under physiologic conditions, are converted into the therapeutically active agents of the present invention (e.g., a compound of Formula (I)). A common method for making a prodrug is to include one or more selected moieties which are hydrolyzed under physiologic conditions to reveal the desired molecule. In other embodiments, the prodrug is converted by an enzymatic activity of the subject. For example, esters or carbonates (e.g., esters or carbonates of alcohols or carboxylic acids) are preferred prodrugs of the present invention. In certain embodiments, some or all of the compounds of Formula (I) in a formulation represented above can be replaced with the corresponding suitable prodrug, e.g., wherein a hydroxyl in the parent compound is presented as an ester or a carbonate or carboxylic acid.

An “effective amount”, as used herein, refers to an amount that is sufficient to achieve a desired biological effect. A “therapeutically effective amount”, as used herein, refers to an amount that is sufficient to achieve a desired therapeutic effect. For example, a therapeutically effective amount can refer to an amount that is sufficient to improve at least one sign or symptom of cancer.

A “response” to a method of treatment can include a decrease in or amelioration of negative symptoms, a decrease in the progression of a disease or symptoms thereof, an increase in beneficial symptoms or clinical outcomes, a lessening of side effects, stabilization of disease, partial or complete remedy of disease, among others.

In some embodiments, the invention provides a compound of formula (I):

or a pharmaceutically acceptable salt and/or prodrug thereof, wherein

-   -   Y is

-   -   Het is heterocyclyl or heteroaryl;     -   R^(1a) is selected from H, halo, hydroxy, cyano, azido, amino,         C₁₋₆alkyl, hydroxyC₁₋₆alkyl, amino-C₁₋₆alkyl,         —O—C(O)—O—C₁₋₆alkyl, C₁₋₆acyloxy, C₁₋₆alkoxy, C₂₋₆alkenyl, and         C₂₋₆alkynyl;     -   R^(1b) is selected from H, halo, C₁₋₆alkyl, hydroxy-C₁₋₆alkyl,         amino-C₁₋₆alkyl, C₂₋₆alkenyl, and C₂₋₆alkynyl;     -   R^(2a) is selected from halo, hydroxy, cyano, azido, amino,         C₁₋₆alkyl, hydroxy-C₁₋₆alkyl, amino-C₁₋₆alkyl, C₁₋₆acyloxy,         —O—C(O)—O—C₁₋₆alkyl, C₁₋₆alkoxy, C₂₋₆alkenyl, and C₂₋₆alkynyl;     -   R^(2b) is selected from halo, C₁₋₆alkyl, C₂₋₆alkenyl, and         C₂₋₆alkynyl, preferably substituted or unsubstituted C₂alkynyl,         most preferably unsubstituted C₂alkynyl;     -   R³ is selected from H and alkyl;     -   R⁴ is selected from H, alkyl, CN, aryl, heteroaryl, —C(O)OR⁹,         —C(O)NR¹¹R¹², —S(O)₂R¹⁰, —P(O)(OR¹¹)(OR¹²), and         —P(O)(OR¹¹)(NR¹³R¹⁴);     -   R⁵ is selected from H, cyano, alkyl, cycloalkylalkyl,         heterocyclylalkyl, aralkyl, heteroaralkyl, and —C(O)OR⁹;     -   R⁶ is selected from —C(O)OR⁹, —C(O)NR¹⁶R¹⁷, and         —P(O)(OR¹¹)(OR¹²);     -   R⁹ is independently selected from H, alkyl, cycloalkyl,         cycloalkylalkyl, heterocyclyl, heterocyclylalkyl, aryl, aralkyl,         heteroaryl, and heteroaralkyl;     -   R¹⁰ is independently selected from alkyl, alkenyl, alkynyl,         amino, cycloalkyl, cycloalkylalkyl, heterocyclyl,         heterocyclylalkyl, aryl, aralkyl, heteroaryl, and heteroaralkyl;         and     -   each R¹¹ and R¹² is independently selected from H, alkyl,         cycloalkyl, cycloalkylalkyl, heterocyclyl, heterocyclylalkyl,         aryl, aralkyl, heteroaryl, heteroaralkyl; or     -   R¹¹ and R¹², together with the nitrogen atom to which they are         attached, form a 5- to 7-membered heterocyclyl;     -   R¹³ is H or alkyl;     -   R¹⁴ is alkyl or aralkyl;     -   each R¹⁵ is independently selected from hydroxy, alkoxy acyloxy         and NR¹³R¹⁴;     -   each R¹⁶ and R¹⁷ is independently selected from H, hydroxy,         alkyl, cycloalkyl, cycloalkylalkyl, heterocyclyl,         heterocyclylalkyl, aryl, aralkyl, heteroaryl, heteroaralkyl; or     -   R¹⁶ and R¹⁷, together with the nitrogen atom to which they are         attached, form a 5- to 7-membered heterocyclyl.

In certain preferred embodiments of Formula I, the included compounds meet the terms of a) and b); or a) and c);

-   -   wherein:     -   a) the compound is not

-   -   b) if R⁴ and R⁶ are each —C(O)OH and R⁵ is benzyl substituted on         the phenyl ring with a heterocyclyl or heteroaryl substituent,         then the phenyl ring substituent is selected from unsubstituted         or substituted pyrrolidinyl, piperazinonyl, piperidonyl,         tetrahydropyrimidonyl, pyridonyl, and pyridyl; and     -   c) if R⁴ is —C(O)OH or tetrazolyl, R⁶ is —C(O)OH, and R⁵ is         benzyl substituted on the phenyl ring with a second phenyl ring,         then either the benzyl phenyl ring or the second phenyl ring is         substituted with —C(O)OR⁹ where R⁹ is H or alkyl.

In some embodiments, the invention provides a compound of formula (II):

or a pharmaceutically acceptable salt and/or prodrug thereof, wherein

-   -   Het is heterocyclyl or heteroaryl;     -   R^(1a) is selected from H, halo, hydroxy, cyano, azido, amino,         C₁₋₆alkyl, hydroxyC₁₋₆alkyl, amino-C₁₋₆alkyl,         —O—C(O)—O—C₁₋₆alkyl, C₁₋₆acyloxy, C₁₋₆alkoxy, C₂₋₆alkenyl, and         C₂₋₆alkynyl;     -   R^(1b) is selected from H, halo, C₁₋₆alkyl, hydroxy-C₁₋₆alkyl,         amino-C₁₋₆alkyl, C₂₋₆alkenyl, and C₂₋₆alkynyl;     -   R^(2a) is selected from halo, hydroxy, cyano, azido, amino,         C₁₋₆alkyl, hydroxy-C₁₋₆alkyl, amino-C₁₋₆alkyl, C₁₋₆acyloxy,         —O—C(O)—O—C₁₋₆alkyl, C₁₋₆alkoxy, C₂₋₆alkenyl, and C₂₋₆alkynyl;     -   R^(2b) is selected from H, halo, C₁₋₆alkyl, C₂₋₆alkenyl, and         C₂₋₆alkynyl;     -   R³ is selected from H and alkyl;     -   R⁴ is selected from alkyl, aryl, heteroaryl, —C(O)OR⁹,         —C(O)NR¹¹R¹², —S(O)₂R¹⁰, —P(O)(OR¹¹)(OR¹²), and         —P(O)(OR¹¹)(NR¹³R¹⁴);     -   R⁵ is selected from H, cyano, alkyl, cycloalkylalkyl,         heterocyclylalkyl, aralkyl, heteroaralkyl, and —C(O)OR⁹;     -   R⁶ is selected from —C(O)OR⁹, —C(O)NR¹¹R¹² and         —P(O)(OR¹¹)(OR¹²);     -   R⁹ is independently selected from H, alkyl, alkenyl, alkynyl,         cycloalkyl, cycloalkylalkyl, heterocyclyl, heterocyclylalkyl,         aryl, aralkyl, heteroaryl, and heteroaralkyl;     -   R¹⁰ is independently selected from alkyl, alkenyl, alkynyl,         amino, cycloalkyl, cycloalkylalkyl, heterocyclyl,         heterocyclylalkyl, aryl, aralkyl, heteroaryl, and heteroaralkyl;         and     -   each R¹¹ and R¹² is independently selected from H, alkyl,         cycloalkyl, cycloalkylalkyl, heterocyclyl, heterocyclylalkyl,         aryl, aralkyl, heteroaryl, heteroaralkyl; or     -   R¹¹ and R¹², together with the nitrogen atom to which they are         attached, form a 5- to 7-membered heterocyclyl;     -   R¹³ is H or alkyl; and     -   R¹⁴ is alkyl or aralkyl;         provided that a), b) and c); or a), b) and d);     -   a) the compound is not

and

-   -   b) R_(2b) is selected from halo, C₂₋₆alkyl, C₂₋₆alkenyl, and         C₂₋₆alkynyl, preferably substituted or unsubstituted C₂alkynyl,         most preferably unsubstituted C₂alkynyl,     -   c) if R⁴ and R⁶ are each —C(O)OH and R¹ is benzyl substituted on         the phenyl ring with a heterocyclyl or heteroaryl substituent,         then the phenyl ring substituent is selected from unsubstituted         or substituted piperidonyl, tetrahydropyrimidonyl, pyridonyl,         and pyridyl; and     -   d) if R⁴ is —C(O)OH or tetrazolyl, R⁶ is —C(O)OH, and R⁵ is         benzyl substituted on the phenyl ring with a second phenyl ring,         then either the benzyl phenyl ring or the second phenyl ring is         substituted with —C(O)OR⁹ where R⁹ is H or alkyl.

In certain preferred embodiments:

-   -   a) the compound is not

and

-   -   b) R_(2b) is selected from halo, C₂₋₆alkyl, C₂₋₆alkenyl, and         C₂₋₆alkynyl, preferably substituted or unsubstituted C₂alkynyl,         most preferably unsubstituted C₂alkynyl; and either     -   c) R⁵ is benzyl substituted on the phenyl ring with a         substituent selected from unsubstituted or substituted         piperidonyl, tetrahydropyrimidonyl, pyridonyl, and pyridyl, or     -   d) R⁵ is benzyl substituted on the phenyl ring with a second         phenyl ring substituted with —C(O)OR⁹ where R⁹ is H or alkyl.

The following paragraphs describe various embodiments of compounds of Formula I or II, which may be combined in any combination as consistent with the formulas as defined above.

In certain embodiments, R^(1a) is H or hydroxy. In certain embodiments, R^(1b) is H or hydroxyl. In other embodiments, R^(1a) is hydroxy and R^(1b) is H.

In some embodiments, R^(2a) is hydroxy or C₁₋₆alkyl. In certain embodiments, R^(2b) is C₂₋₆alkyl, C₂₋₆alkenyl or C₂₋₆alkynyl, preferably substituted or unsubstituted C₂alkynyl, such as ethynyl. In certain preferred embodiments, R^(2a) is Me and R^(2b) is ethynyl. In some embodiments, R^(2a) is hydroxy and R^(2b) is ethyl or vinyl. In other preferred embodiments, R^(2a) is hydroxy and R^(2b) is ethynyl. In some embodiments, R^(2b) is propynyl, butynyl,

or unsubstituted or substituted

In certain preferred embodiments, R³ is H.

In certain embodiments, the compound of Formula (I) has the following structure:

In certain embodiments, the compound of Formula (II) has the following structure:

In certain such embodiments, R^(1a) is in the α-configuration. For example, the compound of Formula (I) may have the structure (IA):

Further, the compound of Formula (II) may have the structure (IIAa):

In alternative embodiments, R^(1a) is in the β-configuration. In some such embodiments, the compound of Formula (I) has the structure (IB):

In some such embodiments, the compound of Formula (II) has the structure (IIBa):

In further embodiments of compounds of Formula (I), e.g., as described above, R^(2a) is in the α-configuration. For example, the compound of Formula (I) may have the structure (IC):

In further preferred embodiments, the compound of Formula (II) has the structure (IICa):

In alternative embodiments, R^(2a) is in the β-configuration. In some such embodiments, the compound of Formula (I) has the structure (ID):

In further preferred embodiments, the compound of Formula (II) has the structure (IIDa):

In certain preferred embodiments, the compound of Formula (I) has the structure (IE):

In further preferred embodiments, the compound of Formula (II) has the structure (IIEa):

In particularly preferred such embodiments, R^(1a) is hydroxy and R^(2a) is hydroxy and R^(2b) is selected from methyl, ethyl, vinyl, and ethynyl, most preferably ethynyl. In most preferred embodiments of the compound of Formula (IE), R^(1a) is hydroxy, R^(2a) is hydroxy, and R^(2b) is ethynyl. In some preferred embodiments of the compound of Formula (IIEa), R^(1a) is hydroxy, R^(2a) is hydroxy, and R^(2b) is ethynyl.

In certain embodiments, Y is

In certain embodiments, R₄ is selected from —C(O)OR⁹, —C(O)NR¹¹R¹², —S(O)₂R¹⁰, and —P(O)(OR¹¹)(OR¹²). In some embodiments, R⁴ is —C(O)OR⁹ and R⁹ is H or alkyl. In other embodiments, R₄ is —C(O)NR¹¹R¹². In certain embodiments, each R¹¹ and R¹² is independently selected from H and alkyl; or R¹¹ and R¹², together with the nitrogen atom to which they are attached, form a 5- to 7-membered heterocyclyl. In other embodiments, R₄ is —S(O)₂R¹⁰ and R¹⁰ is alkyl or aryl.

In some embodiments, R₆ is —C(O)OR⁹ and R⁹ is H or alkyl, e.g., H or C₁₋₆alkyl. In other embodiments, R⁶ is —C(O)NR¹¹R¹². In certain such embodiments, each R¹¹ and R¹² is independently selected from H and alkyl; or R¹¹ and R¹², together with the nitrogen atom to which they are attached, form a 5- to 7-membered heterocyclyl.

In certain preferred embodiments, R₄ and R⁶ are each —C(O)OH, most preferably wherein R⁵ is benzyl, e.g., as discussed in greater detail below.

In certain embodiments, R⁵ is selected from H, alkyl, aralkyl and heteroaralkyl. In certain such embodiments, each alkyl, aralkyl and heteroaralkyl at R⁵ is unsubstituted or substituted with one or more substituents selected from halo, alkyl, alkoxy, carbonyl, amino, amido, cycloalkyl, heterocyclyl, and heteroaryl. In other embodiments, the substituents on the alkyl, aralkyl and heteroaralkyl at R⁵ are selected from halo, haloalkyl, alkoxy, carbonyl, aryl, heterocyclyl, and heteroaryl. In certain embodiments, R⁵ is aralkyl, e.g., substituted on the aryl ring with a 5- to 7-membered heterocyclyl or a 5- to 7-membered heteroaryl. In certain particular embodiments, R⁵ is selected from H, methyl, ethyl, —CH₂-ethynyl, and —CH₂-vinyl. In other embodiments, R⁵ is selected from benzyl, —CH₂-pyridyl, —CH₂-pyridazinyl, —CH₂-oxazolyl, —CH₂-thiophenyl, —CH₂-furanyl, —CH₂-thiazolyl, and —CH₂-benzothiazolyl, preferably benzyl and —CH₂-thiophenyl.

In certain preferred embodiments, R⁵ is benzyl substituted on the phenyl ring (e.g., at a para position) with a heterocyclyl or heteroaryl substituent, preferably wherein the phenyl ring substituent is selected from substituted piperidonyl, tetrahydropyrimidonyl, pyridonyl, and pyridyl. In some embodiments, the phenyl ring substituent is piperazinonyl. In certain such embodiments, the piperidonyl, tetrahydropyrimidonyl, pyridonyl, or pyridyl is substituted with one or more of alkyl, hydroxyalkyl or alkoxyalkyl.

In certain embodiments, R⁵ is aralkyl or heteroaralkyl with a para substituent on the aryl or heteroaryl ring selected from heterocyclyl, heteroaryl, and aryl; and R^(2b) is methyl, ethyl, or C₂₋₆alkynyl.

In certain preferred embodiments, R⁵ is benzyl substituted on the phenyl ring (e.g., at the 4-position) with

In certain embodiments, certain preferred embodiments, R⁵ is benzyl substituted on the phenyl ring (e.g., at the 4-position) with

In some embodiments,

represents

In some embodiments,

represents

In some embodiments, Y is

In certain embodiments, each R¹⁵ is hydroxy.

In certain embodiments, Het is selected from a 6- to 10-membered aryl, a 5- to 8-membered heterocyclyl, a 5- to 8-membered monocyclic or 5- to 10-membered bicyclic heteroaryl, and may be unsubstituted or substituted with one or more substituents selected from halo, alkyl, haloalkyl, alkoxy, carbonyl, amino, amido, alkylthio, alkoxycarbonyl, cycloalkyl, aryl, heterocyclyl and heteroaryl. In some embodiments, the Het substituents are selected from halo, haloalkyl, amino, and heterocyclyl. In certain embodiments, Het is a nitrogen-containing heterocyclyl or heteroaryl, preferably attached to the core ring via a nitrogen atom of the heterocyclyl or heteroaryl ring. In some embodiments, Het is

In other embodiments, Het is

In other embodiments, Het is

wherein

Z is CH or N;

-   -   R^(a) is selected from H, halo, hydroxy, alkyl, thiophenyl,         —NR⁷R⁸, aralkyl, aryl, and heteroaryl, preferably from H, Cl,         —NR⁷R⁸, and phenyl;     -   R^(b) is selected from halo, alkyl, haloalkyl, hydroxyalkyl,         alkylthio, amido, carbonyl, amido, and heteroaryl;     -   R⁷ is selected from H, hydroxy, alkyl, aralkyl, heteroaralkyl,         cycloalkyl, and heterocyclyl; and     -   R⁸ is H or alkyl; or     -   R⁷ and R⁸, together with the nitrogen atom to which they are         attached, form a 4- to 7-membered heterocyclyl ring.

In some embodiments, Het is

In certain embodiments, Z is CH. In other embodiments, Z is N.

In certain embodiments, R^(a) is selected from H, halo, alkyl, thienyl, —NR⁷R⁸, aryl, and heteroaryl, preferably from H, Cl, —NR⁷R⁸, and phenyl. In some embodiments, R^(a) is —NR⁷R⁸.

In certain embodiments, R^(b) is selected from halo, alkyl, hydroxyalkyl, haloalkyl, amido, carbonyl, amido, and heteroaryl. In some embodiments, R^(b) is selected from Cl, —CF₃, carbonyl and —CONH₂.

In some embodiments, Het is

In some embodiments, R⁷ is selected from H, alkyl, aralkyl, heteroaralkyl, cycloalkyl, and heterocyclyl. In certain embodiments, R⁷ is alkyl or cycloalkyl, e.g., where the alkyl or cycloalkyl is unsubstituted or substituted with one or more substituents selected from hydroxy, alkoxy, aryl, amino, and cycloalkyl. In other embodiments, R⁷ is aralkyl or heteroaralkyl, e.g., where the aralkyl or heteroaralkyl is unsubstituted or substituted with halo or alkyl.

In some embodiments, R⁸ is selected from H, methyl, and ethyl.

In other embodiments, R⁷ and R⁸, together with the nitrogen atom to which they are attached, form a heterocyclyl ring, e.g., selected from azetidinyl, morpholino, pyrrolidinyl, and azepanyl.

Methods of Use

Provided herein are methods of inhibiting CD73 in a cell, comprising contacting the cell with a compound of the invention, such as a compound of formula (I), or a pharmaceutically acceptable salt thereof. In certain embodiments, contacting the cell occurs in a subject in need thereof, thereby treating a disease or disorder mediated by adenosine.

Also, disclosed herein are methods of treating a disease or a disorder mediated by adenosine comprising administering a compound the invention, such as a compound of Formula (I), or a pharmaceutically acceptable salt thereof. In some embodiments, disclosed herein are methods of treating cancer comprising administering a compound the invention, such as a compound of Formula (I), or a pharmaceutically acceptable salt thereof.

Adenosine acts on a variety of immune cells to induce immunosuppression, and the immunosuppressive effects of ectonucleotidases that enhance adenosine levels are also associated with enhanced infections of mammalian cells by parasites, fungi, bacteria, and viruses. Apart from immunosuppressive effects, adenosine also has a role in modulating the cardiovascular system (as a vasodilator and cardiac depressor), the central nervous system (CNS) (inducing sedative, anxiolytic and antiepileptic effects), the respiratory system (inducing bronchoconstriction), the kidney (having biphasic action; inducing vasoconstriction at low concentrations and vasodilation at high doses), fat cells (inhibiting lipolysis), and platelets (as an anti-aggregant). Furthermore, adenosine also promotes fibrosis (excess matrix production) in a variety of tissues. Therefore, improved treatments targeting CD73 would provide therapies for treating a wide range of conditions in addition to cancer, including cerebral and cardiac ischemic disease, fibrosis, immune and inflammatory disorders (e.g., inflammatory gut motility disorder), neurological, neurodegenerative and CNS disorders and diseases (e.g., depression, Parkinson's disease), and sleep disorders.

In some embodiments, the disease or the disorder mediated by adenosine is selected from cerebral ischemic disease, cancer, cardiac ischemic disease, depression, fibrosis, an immune disorder, an inflammatory disorder (e.g., inflammatory gut motility disorder), neurological disorder or disease, neurodegenerative disorder or disease (e.g., Parkinson's disease), CNS disorders and diseases, and sleep disorders.

The methods described herein are useful for the treatment of a wide variety of cancers, including bladder cancer, bone cancer, brain cancer (including glioblastoma), breast cancer, cardiac cancer, cervical cancer, colon cancer, colorectal cancer, esophageal cancer, fibrosarcoma, gastric cancer, gastrointestinal cancer, head & neck cancer, Kaposi's sarcoma, kidney cancer (including renal cell adenocarcinoma), leukemia, liver cancer, lung cancer (including non-small cell lung cancer, small cell lung cancer, and mucoepidermoid pulmonary carcinoma), lymphoma, melanoma, myeloma, ovarian cancer (including ovarian adenocarcinoma), pancreatic cancer, penile cancer, prostate cancer, testicular germcell cancer, thymoma and thymic carcinoma.

In some embodiments, the subject has a cancer selected from breast cancer, brain cancer, colon cancer, fibrosarcoma, kidney cancer, lung cancer, melanoma, ovarian cancer, and prostate cancer. In certain embodiments, the subject has a cancer selected from breast cancer, colon cancer, fibrosarcoma, melanoma, ovarian cancer, and prostate cancer. In other embodiments, the subject has a cancer selected from brain cancer, breast cancer, kidney cancer, lung cancer, melanoma, and ovarian cancer. In some embodiments, the subject has head and neck squamous cell carcinoma, ovarian cancer, breast cancer or esophageal cancer.

In other embodiments, the subject has pancreatic cancer, esophageal cancer, stomach cancer, head and neck cancer, colon cancer, lung cancer or kidney cancer. In yet other embodiments, the subject has breast cancer. In some embodiments, the breast cancer is breast adenocarcinoma. In certain embodiments, the breast cancer is triple-negative breast cancer.

In certain embodiments, the methods for treating or preventing cancer can be demonstrated by one or more responses such as increased apoptosis, inhibition of tumor growth, reduction of tumor metastasis, inhibition of tumor metastasis, reduction of microvessel density, decreased neovascularization, inhibition of tumor migration, tumor regression, and increased survival of the subject.

In certain embodiments, the disease or the disorder mediated by adenosine is a disease or disorder mediated by CD73 activity. In some embodiments, the compounds of the invention, such as compounds of Formula (I), are useful as inhibitors of CD73.

In some embodiments, the methods described herein treat or prevent cardiovascular disease using inhibitors of CD73. Mutant genes encoding CD73 lead to extensive calcification of lower-extremity arteries and small joint capsules, which is associated with increased risk of cardiovascular disease (Hilaire et al., N. Engl. J. Med., 364(5): 432-442, 2011).

In some embodiments, the methods disclosed herein treat or prevent cancer using inhibitors of CD73. A CD73 small interfering RNA and anti-CD73 monoclonal antibodies showed a significant effect in treating or preventing cancer (Antonioli et al., Nat. Rev. Cancer, 13: 842-857, 2013). A tight correlation exists between CD73 expression and the ability of cancer cells to migrate, invade, and adhere to the extracellular matrix (ECM) (Antonioli 2013; Antonioli et al., Trends Cancer, 2(2): 95-109, 2016).

In some embodiments, the treatment or prevention of cancer by inhibitors of CD73 can be demonstrated by one or more responses selected from activation, clonal expansion, and homing of tumor-specific T cells (Antonioli 2016). In other embodiments, the methods disclosed herein increase the number of effector T lymphocytes (e.g., cytolytic effector T lymphocytes).

Combination Treatments

In some embodiments, the method of treating or preventing cancer may comprise administering a CD39 inhibitor conjointly with one or more other chemotherapeutic agent(s). In one embodiment, the CD73 inhibitor is a compound of the invention, such as a compound of Formula (I). Other chemotherapeutic agents can include CD73-specific monoclonal antibodies which enhance the effects of other antibodies and therapies because of increased overall immune system activity (lower T-regulatory function and higher T-effector function, etc.) (Antonioli 2016).

In certain embodiments, the method of treating or preventing cancer may comprise administering a compound of the invention conjointly with one or more other chemotherapeutic agent(s).

Chemotherapeutic agents that may be conjointly administered with compounds of the invention include: 1-amino-4-phenylamino-9,10-dioxo-9,10-dihydroanthracene-2-sulfonate (acid blue 25), 1-amino-4-[4-hydroxyphenyl-amino]-9,10-dioxo-9,10-dihydroanthracene-2-sulfonate, 1-amino-4-[4-aminophenylamino]-9,10-dioxo-9,10-dihydroanthracene-2-sulfonate, 1-amino-4-[1-naphthylamino]-9,10-dioxo-9,10-dihydroanthracene-2-sulfonate, 1-amino-4-[4-fluoro-2-carboxyphenylamino]-9,10-dioxo-9,10-dihydroanthracene-2-sulfonate, 1-amino-4-[2-anthracenylamino]-9,10-dioxo-9,10-dihydroanthracene-2-sulfonate, ABT-263, afatinib dimaleate, axitinib, aminoglutethimide, amsacrine, anastrozole, APCP, asparaginase, AZD5363, Bacillus Calmette-Guérin vaccine (beg), bicalutamide, bleomycin, bortezomib, β-methylene-ADP (AOPCP), buserelin, busulfan, cabazitaxel, cabozantinib, campothecin, capecitabine, carboplatin, carfilzomib, carmustine, ceritinib, chlorambucil, chloroquine, cisplatin, cladribine, clodronate, cobimetinib, colchicine, crizotinib, cyclophosphamide, cyproterone, cytarabine, dacarbazine, dactinomycin, daunorubicin, demethoxyviridin, dexamethasone, dichloroacetate, dienestrol, diethylstilbestrol, docetaxel, doxorubicin, epirubicin, eribulin, erlotinib, estradiol, estramustine, etoposide, everolimus, exemestane, filgrastim, fludarabine, fludrocortisone, fluorouracil, fluoxymesterone, flutamide, gefitinib, gemcitabine, genistein, goserelin, GSK1120212, hydroxyurea, idarubicin, ifosfamide, imatinib, interferon, irinotecan, ixabepilone, lenalidomide, letrozole, leucovorin, leuprolide, levamisole, lomustine, lonidamine, mechlorethamine, medroxyprogesterone, megestrol, melphalan, mercaptopurine, mesna, metformin, methotrexate, miltefosine, mitomycin, mitotane, mitoxantrone, MK-2206, mutamycin, N-(4-sulfamoylphenylcarbamothioyl) pivalamide, NF279, NF449, nilutamide, nocodazole, octreotide, olaparib, oxaliplatin, paclitaxel, pamidronate, pazopanib, pemexetred, pentostatin, perifosine, PF-04691502, plicamycin, pomalidomide, porfimer, PPADS, procarbazine, quercetin, raltitrexed, ramucirumab, reactive blue 2, rituximab, rolofylline, romidepsin, rucaparib, selumetinib, sirolimus, sodium 2,4-dinitrobenzenesulfonate, sorafenib, streptozocin, sunitinib, suramin, talazoparib, tamoxifen, temozolomide, temsirolimus, teniposide, testosterone, thalidomide, thioguanine, thiotepa, titanocene dichloride, tonapofylline, topotecan, trametinib, trastuzumab, tretinoin, veliparib, vinblastine, vincristine, vindesine, vinorelbine, and vorinostat (SAHA). In other embodiments, chemotherapeutic agents that may be conjointly administered with compounds of the invention include: ABT-263, dexamethasone, 5-fluorouracil, PF-04691502, romidepsin, and vorinostat (SAHA). In other embodiments, chemotherapeutic agents that may be conjointly administered with compounds of the invention include: 1-amino-4-phenylamino-9,10-dioxo-9,10-dihydroanthracene-2-sulfonate (acid blue 25), 1-amino-4-[4-hydroxyphenyl-amino]-9,10-dioxo-9,10-dihydroanthracene-2-sulfonate, 1-amino-4-[4-aminophenylamino]-9,10-dioxo-9,10-dihydroanthracene-2-sulfonate, 1-amino-4-[1-naphthylamino]-9,10-dioxo-9,10-dihydroanthracene-2-sulfonate, 1-amino-4-[4-fluoro-2-carboxyphenylamino]-9,10-dioxo-9,10-dihydroanthracene-2-sulfonate, 1-amino-4-[2-anthracenylamino]-9,10-dioxo-9,10-dihydroanthracene-2-sulfonate, APCP, β-methylene-ADP (AOPCP), capecitabine, cladribine, cytarabine, fludarabine, doxorubicin, gemcitabine, N-(4-sulfamoylphenylcarbamothioyl) pivalamide, NF279, NF449, PPADS, quercetin, reactive blue 2, rolofylline sodium 2,4-dinitrobenzenesulfonate, sumarin, and tonapofylline.

Many combination therapies have been developed for the treatment of cancer. In certain embodiments, compounds of the invention (e.g., compounds of Formula (I)) may be conjointly administered with a combination therapy. Examples of combination therapies with which compounds of the invention may be conjointly administered are included in Table 1.

TABLE 1 Exemplary combinatorial therapies for the treatment of cancer Name Therapeutic agents ABV Doxorubicin, Bleomycin, Vinblastine ABVD Doxorubicin, Bleomycin, Vinblastine, Dacarbazine AC (Breast) Doxorubicin, Cyclophosphamide AC Doxorubicin, Cisplatin (Sarcoma) AC (Neuro- Cyclophosphamide, Doxorubicin blastoma) ACE Cyclophosphamide, Doxorubicin, Etoposide ACe Cyclophosphamide, Doxorubicin AD Doxorubicin, Dacarbazine AP Doxorubicin, Cisplatin ARAC-DNR Cytarabine, Daunorubicin B-CAVe Bleomycin, Lomustine, Doxorubicin, Vinblastine BCVPP Carmustine, Cyclophosphamide, Vinblastine, Procarbazine, Prednisone BEACOPP Bleomycin, Etoposide, Doxorubicin, Cyclophosphamide, Vincristine, Procarbazine, Prednisone, Filgrastim BEP Bleomycin, Etoposide, Cisplatin BIP Bleomycin, Cisplatin, Ifosfamide, Mesna BOMP Bleomycin, Vincristine, Cisplatin, Mitomycin CA Cytarabine, Asparaginase CABO Cisplatin, Methotrexate, Bleomycin, Vincristine CAF Cyclophosphamide, Doxorubicin, Fluorouracil CAL-G Cyclophosphamide, Daunorubicin, Vincristine, Prednisone, Asparaginase CAMP Cyclophosphamide, Doxorubicin, Methotrexate, Procarbazine CAP Cyclophosphamide, Doxorubicin, Cisplatin CAV Cyclophosphamide, Doxorubicin, Vincristine CAVE ADD CAV and Etoposide CA-VP16 Cyclophosphamide, Doxorubicin, Etoposide CC Cyclophosphamide, Carboplatin CDDP/ Cisplatin, Etoposide VP-16 CEF Cyclophosphamide, Epirubicin, Fluorouracil CEPP(B) Cyclophosphamide, Etoposide, Prednisone, with or without/Bleomycin CEV Cyclophosphamide, Etoposide, Vincristine CF Cisplatin, Fluorouracil or Carboplatin Fluorouracil CHAP Cyclophosphamide or Cyclophosphamide, Altretamine, Doxorubicin, Cisplatin ChlVPP Chlorambucil, Vinblastine, Procarbazine, Prednisone CHOP Cyclophosphamide, Doxorubicin, Vincristine, Prednisone CHOP- Add Bleomycin to CHOP BLEO CISCA Cyclophosphamide, Doxorubicin, Cisplatin CLD-BOMP Bleomycin, Cisplatin, Vincristine, Mitomycin CMF Methotrexate, Fluorouracil, Cyclophosphamide CMFP Cyclophosphamide, Methotrexate, Fluorouracil, Prednisone CMFVP Cyclophosphamide, Methotrexate, Fluorouracil, Vincristine, Prednisone CMV Cisplatin, Methotrexate, Vinblastine CNF Cyclophosphamide, Mitoxantrone, Fluorouracil CNOP Cyclophosphamide, Mitoxantrone, Vincristine, Prednisone COB Cisplatin, Vincristine, Bleomycin CODE Cisplatin, Vincristine, Doxorubicin, Etoposide COMLA Cyclophosphamide, Vincristine, Methotrexate, Leucovorin, Cytarabine COMP Cyclophosphamide, Vincristine, Methotrexate, Prednisone Cooper Cyclophosphamide, Methotrexate, Fluorouracil, Regimen Vincristine, Prednisone COP Cyclophosphamide, Vincristine, Prednisone COPE Cyclophosphamide, Vincristine, Cisplatin, Etoposide COPP Cyclophosphamide, Vincristine, Procarbazine, Prednisone CP(Chronic Chlorambucil, Prednisone lymphocytic leukemia) CP (Ovarian Cyclophosphamide, Cisplatin Cancer) CVD Cisplatin, Vinblastine, Dacarbazine CVI Carboplatin, Etoposide, Ifosfamide, Mesna CVP Cyclophosphamide, Vincristine, Prednisome CVPP Lomustine, Procarbazine, Prednisone CYVADIC Cyclophosphamide, Vincristine, Doxorubicin, Dacarbazine DA Daunorubicin, Cytarabine DAT Daunorubicin, Cytarabine, Thioguanine DAV Daunorubicin, Cytarabine, Etoposide DCT Daunorubicin, Cytarabine, Thioguanine DHAP Cisplatin, Cytarabine, Dexamethasone DI Doxorubicin, Ifosfamide DTIC/ Dacarbazine, Tamoxifen Tamoxifen DVP Daunorubicin, Vincristine, Prednisone EAP Etoposide, Doxorubicin, Cisplatin EC Etoposide, Carboplatin EFP Etoposie, Fluorouracil, Cisplatin ELF Etoposide, Leucovorin, Fluorouracil EMA 86 Mitoxantrone, Etoposide, Cytarabine EP Etoposide, Cisplatin EVA Etoposide, Vinblastine FAC Fluorouracil, Doxorubicin, Cyclophosphamide FAM Fluorouracil, Doxorubicin, Mitomycin FAMTX Methotrexate, Leucovorin, Doxorubicin FAP Fluorouracil, Doxorubicin, Cisplatin F-CL Fluorouracil, Leucovorin FEC Fluorouracil, Cyclophosphamide, Epirubicin FED Fluorouracil, Etoposide, Cisplatin FL Flutamide, Leuprolide FZ Flutamide, Goserelin acetate implant HDMTX Methotrexate, Leucovorin Hexa-CAF Altretamine, Cyclophosphamide, Methotrexate, Fluorouracil IDMTX/ Methotrexate, Mercaptopurine, Leucovorin 6-MP IE Ifosfamide, Etoposie, Mesna IfoVP Ifosfamide, Etoposide, Mesna IPA Ifosfamide, Cisplatin, Doxorubicin M-2 Vincristine, Carmustine, Cyclophosphamide, Prednisone, Melphalan MAC-III Methotrexate, Leucovorin, Dactinomycin, Cyclophosphamide MACC Methotrexate, Doxorubicin, Cyclophosphamide, Lomustine MACOP-B Methotrexate, Leucovorin, Doxorubicin, Cyclophosphamide, Vincristine, Bleomycin, Prednisone MAID Mesna, Doxorubicin, Ifosfamide, Dacarbazine m-BACOD Bleomycin, Doxorubicin, Cyclophosphamide, Vincristine, Dexamethasone, Methotrexate, Leucovorin MBC Methotrexate, Bleomycin, Cisplatin MC Mitoxantrone, Cytarabine MF Methotrexate, Fluorouracil, Leucovorin MICE Ifosfamide, Carboplatin, Etoposide, Mesna MINE Mesna, Ifosfamide, Mitoxantrone, Etoposide mini-BEAM Carmustine, Etoposide, Cytarabine, Melphalan MOBP Bleomycin, Vincristine, Cisplatin, Mitomycin MOP Mechlorethamine, Vincristine, Procarbazine MOPP Mechlorethamine, Vincristine, Procarbazine, Prednisone MOPP/ABV Mechlorethamine, Vincristine, Procarbazine, Prednisone, Doxorubicin, Bleomycin, Vinblastine MP (multiple Melphalan, Prednisone myeloma) MP (prostate Mitoxantrone, Prednisone cancer) MTX/6-MO Methotrexate, Mercaptopurine MTX/6- Methotrexate, Mercaptopurine, Vincristine, Prednisone MP/VP MTX- Methotrexate, Leucovorin, Cisplatin, Doxorubicin CDDPAdr MV (breast Mitomycin, Vinblastine cancer) MV (acute Mitoxantrone, Etoposide myelocytic leukemia) M-VAC Vinblastine, Doxorubicin, Cisplatin Methotrexate MVP Vinblastine, Cisplatin Mitomycin MVPP Mechlorethamine, Vinblastine, Procarbazine, Prednisone NFL Mitoxantrone, Fluorouracil, Leucovorin NOVP Mitoxantrone, Vinblastine, Vincristine OPA Vincristine, Prednisone, Doxorubicin OPPA Add Procarbazine to OPA. PAC Cisplatin, Doxorubicin PAC-I Cisplatin, Doxorubicin, Cyclophosphamide PA-CI Cisplatin, Doxorubicin PCV Lomustine, Procarbazine, Vincristine PFL Cisplatin, Fluorouracil, Leucovorin POC Prednisone, Vincristine, Lomustine ProMACE Prednisone, Methotrexate, Leucovorin, Doxorubicin, Cyclophosphamide, Etoposide ProMACE/ Prednisone, Doxorubicin, Cyclophosphamide, Etoposide, cytaBOM Cytarabine, Bleomycin, Vincristine, Methotrexate, Leucovorin, Cotrimoxazole PRoMACE/ Prednisone, Doxorubicin, Cyclophosphamide, Etoposide, MOPP Mechlorethamine, Vincristine, Procarbazine, Methotrexate, Leucovorin Pt/VM Cisplatin, Teniposide PVA Prednisone, Vincristine, Asparaginase PVB Cisplatin, Vinblastine, Bleomycin PVDA Prednisone, Vincristine, Daunorubicin, Asparaginase SMF Streptozocin, Mitomycin, Fluorouracil TAD Mechlorethamine, Doxorubicin, Vinblastine, Vincristine, Bleomycin, Etoposide, Prednisone TTT Methotrexate, Cytarabine, Hydrocortisone Topo/CTX Cyclophosphamide, Topotecan, Mesna VAB-6 Cyclophosphamide, Dactinomycin, Vinblastine, Cisplatin, Bleomycin VAC Vincristine, Dactinomycin, Cyclophosphamide VACAdr Vincristine, Cyclophosphamide, Doxorubicin, Dactinomycin, Vincristine VAD Vincristine, Doxorubicin, Dexamethasone VATH Vinblastine, Doxorubicin, Thiotepa, Flouxymesterone VBAP Vincristine, Carmustine, Doxorubicin, Prednisone VBCMP Vincristine, Carmustine, Melphalan, Cyclophosphamide, Prednisone VC Vinorelbine, Cisplatin VCAP Vincristine, Cyclophosphamide, Doxorubicin, Prednisone VD Vinorelbine, Doxorubicin VelP Vinblastine, Cisplatin, Ifosfamide, Mesna VIP Etoposide, Cisplatin, Ifosfamide, Mesna VM Mitomycin, Vinblastine VMCP Vincristine, Melphalan, Cyclophosphamide, Prednisone VP Etoposide, Cisplatin V-TAD Etoposide, Thioguanine, Daunorubicin, Cytarabine 5 + 2 Cytarabine, Daunorubicin, Mitoxantrone 7 + 3 Cytarabine with/, Daunorubicin or Idarubicin or Mitoxantrone “8 in 1” Methylprednisolone, Vincristine, Lomustine, Procarbazine, Hydroxyurea, Cisplatin, Cytarabine, Dacarbazine

In some embodiments, the chemotherapeutic agents that may be conjointly administered with compounds of the invention, such as a compound of Formula (I), include a CD39 inhibitor. CD39 or ecto-nucleoside triphosphate diphosphohydrolase 1 (E-NTPDase1 or ENTPD 1) is a membrane-bound enzyme that catalyzes the conversion of extracellular adenosine triphosphate (ATP) and/or ADP (adenosine diphosphate) to adenosine monophosphate (AMP). In one embodiment, the CD39 inhibitor is poly oxometalate-1 (POM-1).

In other embodiments, the chemotherapeutic agents that may be conjointly administered with compounds of the invention, such as a compound of Formula (I), include known CD73 inhibitors. In some embodiments, the CD73 inhibitor is an anthraquinone derivative (Baqi et al., J. Med. Chem., 53(5): 2076-2086, 2010, herein incorporated by reference). In other embodiments, the CD73 inhibitor is an sulfonic acid derivative (Raza et al., Med. Chem., 8: 1133-1139, 2012, herein incorporated by reference). In yet other embodiments, the CD73 inhibitor is selected from 1-amino-4-phenylamino-9,10-dioxo-9,10-dihydroanthracene-2-sulfonate (acid blue 25), 1-amino-4-[4-hydroxyphenyl-amino]-9,10-dioxo-9,10-dihydroanthracene-2-sulfonate, 1-amino-4-[4-aminophenylamino]-9,10-dioxo-9,10-dihydroanthracene-2-sulfonate, 1-amino-4-[1-naphthylamino]-9,10-dioxo-9,10-dihydroanthracene-2-sulfonate, 1-amino-4-[4-fluoro-2-carboxyphenylamino]-9,10-dioxo-9,10-dihydroanthracene-2-sulfonate, 1-amino-4-[2-anthracenylamino]-9,10-dioxo-9,10-dihydroanthracene-2-sulfonate, sodium 2,4-dinitrobenzenesulfonate, N-(4-sulfamoylphenylcarbamothioyl) pivalamide, APCP, β-methylene-ADP (AOPCP), PPADS, NF279, NF449, quercetin, reactive blue 2, and sumarin (Baqi 2010; Raza 2012).

In certain embodiments, the combination of a compound of the invention, such as a compound of Formula (I), with a second CD73 inhibitor or a CD39 inhibitor may have a synergistic effect in the treatment of cancer and other diseases or disorders mediated by adenosine. Without wishing to be bound by any theory, this synergy may be observed because CD39 and CD73 are often on different cell types. The hypoxic tumor microenvironment also induces greater levels of CD39 and CD73.

In some embodiments, the chemotherapeutic agents that may be conjointly administered with compounds of the invention, such as a compound of Formula (I), include an adenosine receptor inhibitor. In other embodiments, the adenosine receptor inhibitor is selected from rolofylline, tonapofylline, ATL-444, istradefylline, MSX-3, preladenant, SCH-58,261, SCH-412,348, SCH-442,416, ST-1535, VER-6623, VER-6947, VER-7835, vipadenant, and ZM-241,385. In some embodiments, the adenosine receptor inhibitor targets the A_(2A) receptor as this subtype is predominantly expressed in most immune cells.

In other embodiments, the chemotherapeutic agents that may be conjointly administered with compounds of the invention, such as a compound of Formula (I), include a nucleoside-based drug. In certain embodiments, the nucleoside-based drug is selected from gemcitabine, capecitabine, cytarabine, fludarabine and cladribine.

In further embodiments, the combination therapy comprises a compound of the invention, such as a compound of Formula (I), conjointly administered with an anthracycline.

In other embodiments, the combination therapy comprises a compound of the invention, such as a compound of Formula (I), conjointly administered with doxorubicin. Combination treatment with an anti-CD73 antibody and doxorubicin has demonstrated a significant chemotherapeutic effect (Young et al., Cancer Discov., 4(8): 1-10, 2014, herein incorporated by reference).

In certain embodiments, the combination therapy comprises a compound of the invention, such as a compound of Formula (I), conjointly administered with an A_(2A) receptor inhibitor and an anthracycline. In some embodiments, the anthracycline is doxorubicin. Combination treatment with an anti-CD73 antibody, an A_(2A) receptor inhibitor, and doxorubicin has demonstrated an increased chemotherapeutic effect (Antonioli 2013).

In certain embodiments, the conjoint therapies of the invention comprise conjoint administration with other types of chemotherapeutic agents, such as immuno-oncology agents. Cancer cells often have specific cell surface antigens that can be recognized by the immune system. Thus, immuno-oncology agents, such as monoclonal antibodies, can selectively bind to cancer cell antigens and effect cell death. Other immuno-oncology agents can suppress tumor-mediated inhibition of the native immune response or otherwise activate the immune response and thus facilitate recognition of the tumor by the immune system. Exemplary antibody immuno-oncology agents, include, but are not limited to, abagovomab, adecatumumab, afutuzumab, alemtuzumab, anatumomab mafenatox, apolizumab, blinatumomab, BMS-936559, catumaxomab, durvalumab, epacadostat, epratuzumab, indoximod, inotuzumab ozogamicin, intelumumab, ipilimumab, isatuximab, lambrolizumab, MED14736, MPDL3280A, nivolumab, obinutuzumab, ocaratuzumab, ofatumumab, olatatumab, pembrolizumab, pidilizumab, rituximab, ticilimumab, samalizumab, and tremelimumab. In some embodiments, the antibody immune-oncology agents are selected from anti-CD73 monoclonal antibody (mAb), anti-CD39 mAb, anti-PD-1 mAb, and anti-CTLA4 mAb. Thus, in some embodiments, the methods of the invention comprise conjoint administration of one or more immuno-oncology agents, such as the agents mentioned above.

In some embodiments, the combination therapy comprises a compound of the invention, such as a compound of Formula (I), conjointly administered with anti-PD-1 therapy and anti-CTLA4 therapy. Combination treatment with an anti-CD73 monoclonal antibody (mAb), anti-PD-1 mAb, and anti-CTLA4 mAb showed a significant chemotherapeutic effect (Young 2014; Antonioli 2013).

In some embodiments, the combination therapy comprises conjoint administration of a compound of the invention, such as a compound of Formula (I), with anti-PD-1 therapy. In certain embodiments, the combination therapy comprises conjoint administration of a compound of the invention, such as a compound of Formula (I), with oxaliplatin. In other embodiments, the combination therapy comprises conjoint administration of a compound of the invention, such as a compound of Formula (I), with doxorubicin.

In certain embodiments, a compound of the invention may be conjointly administered with non-chemical methods of cancer treatment. In certain embodiments, a compound of the invention may be conjointly administered with radiation therapy. In certain embodiments, a compound of the invention may be conjointly administered with surgery, with thermoablation, with focused ultrasound therapy, with cryotherapy, or with any combination of these.

In certain embodiments, compounds of the invention may be conjointly administered with one or more other compounds of the invention. Moreover, such combinations may be conjointly administered with other therapeutic agents, such as other agents suitable for the treatment of cancer, immunological or neurological diseases, such as the agents identified above. In certain embodiments, conjointly administering one or more additional chemotherapeutic agents with a compound of the invention provides a synergistic effect. In certain embodiments, conjointly administering one or more additional chemotherapeutic agents provides an additive effect.

Pharmaceutical Compositions

In certain embodiments, the present invention provides a pharmaceutical preparation suitable for use in a human patient, comprising any of the compounds shown above (e.g., a compound of the invention, such as a compound of formula (I), and one or more pharmaceutically acceptable excipients. In certain embodiments, the pharmaceutical preparations may be for use in treating or preventing a condition or disease as described herein. Any of the disclosed compounds may be used in the manufacture of medicaments for the treatment of any diseases or conditions disclosed herein.

The compositions and methods of the present invention may be utilized to treat a subject in need thereof. In certain embodiments, the subject is a mammal such as a human, or a non-human mammal. When administered to subject, such as a human, the composition or the compound is preferably administered as a pharmaceutical composition comprising, for example, a compound of the invention and a pharmaceutically acceptable carrier. Pharmaceutically acceptable carriers are well known in the art and include, for example, aqueous solutions such as water or physiologically buffered saline or other solvents or vehicles such as glycols, glycerol, oils such as olive oil, or injectable organic esters. In a preferred embodiment, when such pharmaceutical compositions are for human administration, particularly for invasive routes of administration (i.e., routes, such as injection or implantation, that circumvent transport or diffusion through an epithelial barrier), the aqueous solution is pyrogen-free, or substantially pyrogen-free. The excipients can be chosen, for example, to effect delayed release of an agent or to selectively target one or more cells, tissues or organs. The pharmaceutical composition can be in dosage unit form such as tablet, capsule (including sprinkle capsule and gelatin capsule), granule, lyophile for reconstitution, powder, solution, syrup, suppository, injection or the like. The composition can also be present in a transdermal delivery system, e.g., a skin patch. The composition can also be present in a solution suitable for topical administration, such as an eye drop.

A pharmaceutically acceptable carrier can contain physiologically acceptable agents that act, for example, to stabilize, increase solubility or to increase the absorption of a compound such as a compound of the invention. Such physiologically acceptable agents include, for example, carbohydrates, such as glucose, sucrose or dextrans, antioxidants, such as ascorbic acid or glutathione, chelating agents, low molecular weight proteins or other stabilizers or excipients. The choice of a pharmaceutically acceptable carrier, including a physiologically acceptable agent, depends, for example, on the route of administration of the composition. The preparation or pharmaceutical composition can be a self-emulsifying drug delivery system or a self-microemulsifying drug delivery system. The pharmaceutical composition (preparation) also can be a liposome or other polymer matrix, which can have incorporated therein, for example, a compound of the invention. Liposomes, for example, which comprise phospholipids or other lipids, are nontoxic, physiologically acceptable and metabolizable carriers that are relatively simple to make and administer.

The phrase “pharmaceutically acceptable” is employed herein to refer to those compounds, materials, compositions, and/or dosage forms which are, within the scope of sound medical judgment, suitable for use in contact with the tissues of a subject without excessive toxicity, irritation, allergic response, or other problem or complication, commensurate with a reasonable benefit/risk ratio.

The phrase “pharmaceutically acceptable carrier” as used herein means a pharmaceutically acceptable material, composition or vehicle, such as a liquid or solid filler, diluent, excipient, solvent or encapsulating material. Each carrier must be “acceptable” in the sense of being compatible with the other ingredients of the formulation and not injurious to the subject. Some examples of materials which can serve as pharmaceutically acceptable carriers include: (1) sugars, such as lactose, glucose and sucrose; (2) starches, such as corn starch and potato starch; (3) cellulose, and its derivatives, such as sodium carboxymethyl cellulose, ethyl cellulose and cellulose acetate; (4) powdered tragacanth; (5) malt; (6) gelatin; (7) talc; (8) excipients, such as cocoa butter and suppository waxes; (9) oils, such as peanut oil, cottonseed oil, safflower oil, sesame oil, olive oil, corn oil and soybean oil; (10) glycols, such as propylene glycol; (11) polyols, such as glycerin, sorbitol, mannitol and polyethylene glycol; (12) esters, such as ethyl oleate and ethyl laurate; (13) agar; (14) buffering agents, such as magnesium hydroxide and aluminum hydroxide; (15) alginic acid; (16) pyrogen-free water; (17) isotonic saline; (18) Ringer's solution; (19) ethyl alcohol; (20) phosphate buffer solutions; and (21) other non-toxic compatible substances employed in pharmaceutical formulations.

A pharmaceutical composition (preparation) can be administered to a subject by any of a number of routes of administration including, for example, orally (for example, drenches as in aqueous or non-aqueous solutions or suspensions, tablets, capsules (including sprinkle capsules and gelatin capsules), boluses, powders, granules, pastes for application to the tongue); absorption through the oral mucosa (e.g., sublingually); anally, rectally or vaginally (for example, as a pessary, cream or foam); parenterally (including intramuscularly, intravenously, subcutaneously or intrathecally as, for example, a sterile solution or suspension); nasally; intraperitoneally; subcutaneously; transdermally (for example as a patch applied to the skin); and topically (for example, as a cream, ointment or spray applied to the skin, or as an eye drop). The compound may also be formulated for inhalation. In certain embodiments, a compound may be simply dissolved or suspended in sterile water. Details of appropriate routes of administration and compositions suitable for same can be found in, for example, U.S. Pat. Nos. 6,110,973, 5,763,493, 5,731,000, 5,541,231, 5,427,798, 5,358,970 and 4,172,896, as well as in patents cited therein.

The formulations may conveniently be presented in unit dosage form and may be prepared by any methods well known in the art of pharmacy. The amount of active ingredient which can be combined with a carrier material to produce a single dosage form will vary depending upon the subject being treated, the particular mode of administration. The amount of active ingredient that can be combined with a carrier material to produce a single dosage form will generally be that amount of the compound which produces a therapeutic effect. Generally, out of one hundred percent, this amount will range from about 1 percent to about ninety-nine percent of active ingredient, preferably from about 5 percent to about 70 percent, most preferably from about 10 percent to about 30 percent.

Methods of preparing these formulations or compositions include the step of bringing into association an active compound, such as a compound of the invention, with the carrier and, optionally, one or more accessory ingredients. In general, the formulations are prepared by uniformly and intimately bringing into association a compound of the present invention with liquid carriers, or finely divided solid carriers, or both, and then, if necessary, shaping the product.

Formulations of the invention suitable for oral administration may be in the form of capsules (including sprinkle capsules and gelatin capsules), cachets, pills, tablets, lozenges (using a flavored basis, usually sucrose and acacia or tragacanth), lyophile, powders, granules, or as a solution or a suspension in an aqueous or non-aqueous liquid, or as an oil-in-water or water-in-oil liquid emulsion, or as an elixir or syrup, or as pastilles (using an inert base, such as gelatin and glycerin, or sucrose and acacia) and/or as mouth washes and the like, each containing a predetermined amount of a compound of the present invention as an active ingredient. Compositions or compounds may also be administered as a bolus, electuary or paste.

To prepare solid dosage forms for oral administration (capsules (including sprinkle capsules and gelatin capsules), tablets, pills, dragees, powders, granules and the like), the active ingredient is mixed with one or more pharmaceutically acceptable carriers, such as sodium citrate or dicalcium phosphate, and/or any of the following: (1) fillers or extenders, such as starches, lactose, sucrose, glucose, mannitol, and/or silicic acid; (2) binders, such as, for example, carboxymethylcellulose, alginates, gelatin, polyvinyl pyrrolidone, sucrose and/or acacia; (3) humectants, such as glycerol; (4) disintegrating agents, such as agar-agar, calcium carbonate, potato or tapioca starch, alginic acid, certain silicates, and sodium carbonate; (5) solution retarding agents, such as paraffin; (6) absorption accelerators, such as quaternary ammonium compounds; (7) wetting agents, such as, for example, cetyl alcohol and glycerol monostearate; (8) absorbents, such as kaolin and bentonite clay; (9) lubricants, such a talc, calcium stearate, magnesium stearate, solid polyethylene glycols, sodium lauryl sulfate, and mixtures thereof; (10) complexing agents, such as, modified and unmodified cyclodextrins; and (11) coloring agents. In the case of capsules (including sprinkle capsules and gelatin capsules), tablets and pills, the pharmaceutical compositions may also comprise buffering agents. Solid compositions of a similar type may also be employed as fillers in soft and hard-filled gelatin capsules using such excipients as lactose or milk sugars, as well as high molecular weight polyethylene glycols and the like.

A tablet may be made by compression or molding, optionally with one or more accessory ingredients. Compressed tablets may be prepared using binder (for example, gelatin or hydroxypropylmethyl cellulose), lubricant, inert diluent, preservative, disintegrant (for example, sodium starch glycolate or cross-linked sodium carboxymethyl cellulose), surface-active or dispersing agent. Molded tablets may be made by molding in a suitable machine a mixture of the powdered compound moistened with an inert liquid diluent.

The tablets, and other solid dosage forms of the pharmaceutical compositions, such as dragees, capsules (including sprinkle capsules and gelatin capsules), pills and granules, may optionally be scored or prepared with coatings and shells, such as enteric coatings and other coatings well known in the pharmaceutical-formulating art. They may also be formulated so as to provide slow or controlled release of the active ingredient therein using, for example, hydroxypropylmethyl cellulose in varying proportions to provide the desired release profile, other polymer matrices, liposomes and/or microspheres. They may be sterilized by, for example, filtration through a bacteria-retaining filter, or by incorporating sterilizing agents in the form of sterile solid compositions that can be dissolved in sterile water, or some other sterile injectable medium immediately before use. These compositions may also optionally contain opacifying agents and may be of a composition that they release the active ingredient(s) only, or preferentially, in a certain portion of the gastrointestinal tract, optionally, in a delayed manner. Examples of embedding compositions that can be used include polymeric substances and waxes. The active ingredient can also be in microencapsulated form, if appropriate, with one or more of the above-described excipients.

Liquid dosage forms useful for oral administration include pharmaceutically acceptable emulsions, lyophiles for reconstitution, microemulsions, solutions, suspensions, syrups and elixirs. In addition to the active ingredient, the liquid dosage forms may contain inert diluents commonly used in the art, such as, for example, water or other solvents, cyclodextrins and derivatives thereof, solubilizing agents and emulsifiers, such as ethyl alcohol, isopropyl alcohol, ethyl carbonate, ethyl acetate, benzyl alcohol, benzyl benzoate, propylene glycol, 1,3-butylene glycol, oils (in particular, cottonseed, groundnut, corn, germ, olive, castor and sesame oils), glycerol, tetrahydrofuryl alcohol, polyethylene glycols and fatty acid esters of sorbitan, and mixtures thereof.

Besides inert diluents, the oral compositions can also include adjuvants such as wetting agents, emulsifying and suspending agents, sweetening, flavoring, coloring, perfuming and preservative agents.

Suspensions, in addition to the active compounds, may contain suspending agents as, for example, ethoxylated isostearyl alcohols, polyoxyethylene sorbitol and sorbitan esters, microcrystalline cellulose, aluminum metahydroxide, bentonite, agar-agar and tragacanth, and mixtures thereof.

Formulations of the pharmaceutical compositions for rectal, vaginal, or urethral administration may be presented as a suppository, which may be prepared by mixing one or more active compounds with one or more suitable nonirritating excipients or carriers comprising, for example, cocoa butter, polyethylene glycol, a suppository wax or a salicylate, and which is solid at room temperature, but liquid at body temperature and, therefore, will melt in the rectum or vaginal cavity and release the active compound.

Formulations of the pharmaceutical compositions for administration to the mouth may be presented as a mouthwash, or an oral spray, or an oral ointment.

Alternatively or additionally, compositions can be formulated for delivery via a catheter, stent, wire, or other intraluminal device. Delivery via such devices may be especially useful for delivery to the bladder, urethra, ureter, rectum, or intestine.

Formulations which are suitable for vaginal administration also include pessaries, tampons, creams, gels, pastes, foams or spray formulations containing such carriers as are known in the art to be appropriate.

Dosage forms for the topical or transdermal administration include powders, sprays, ointments, pastes, creams, lotions, gels, solutions, patches and inhalants. The active compound may be mixed under sterile conditions with a pharmaceutically acceptable carrier, and with any preservatives, buffers, or propellants that may be required.

The ointments, pastes, creams and gels may contain, in addition to an active compound, excipients, such as animal and vegetable fats, oils, waxes, paraffins, starch, tragacanth, cellulose derivatives, polyethylene glycols, silicones, bentonites, silicic acid, talc and zinc oxide, or mixtures thereof.

Powders and sprays can contain, in addition to an active compound, excipients such as lactose, talc, silicic acid, aluminum hydroxide, calcium silicates and polyamide powder, or mixtures of these substances. Sprays can additionally contain customary propellants, such as chlorofluorohydrocarbons and volatile unsubstituted hydrocarbons, such as butane and propane.

Transdermal patches have the added advantage of providing controlled delivery of a compound of the present invention to the body. Such dosage forms can be made by dissolving or dispersing the active compound in the proper medium. Absorption enhancers can also be used to increase the flux of the compound across the skin. The rate of such flux can be controlled by either providing a rate controlling membrane or dispersing the compound in a polymer matrix or gel.

Ophthalmic formulations, eye ointments, powders, solutions and the like, are also contemplated as being within the scope of this invention. Exemplary ophthalmic formulations are described in U.S. Publication Nos. 2005/0080056, 2005/0059744, 2005/0031697 and 2005/004074 and U.S. Pat. No. 6,583,124, the contents of which are incorporated herein by reference. If desired, liquid ophthalmic formulations have properties similar to that of lacrimal fluids, aqueous humor or vitreous humor or are compatible with such fluids. A preferred route of administration is local administration (e.g., topical administration, such as eye drops, or administration via an implant).

The phrases “parenteral administration” and “administered parenterally” as used herein means modes of administration other than enteral and topical administration, usually by injection, and includes, without limitation, intravenous, intramuscular, intraarterial, intrathecal, intracapsular, intraorbital, intracardiac, intradermal, intraperitoneal, transtracheal, subcutaneous, subcuticular, intraarticular, subcapsular, subarachnoid, intraspinal and intrasternal injection and infusion.

Pharmaceutical compositions suitable for parenteral administration comprise one or more active compounds in combination with one or more pharmaceutically acceptable sterile isotonic aqueous or nonaqueous solutions, dispersions, suspensions or emulsions, or sterile powders which may be reconstituted into sterile injectable solutions or dispersions just prior to use, which may contain antioxidants, buffers, bacteriostats, solutes which render the formulation isotonic with the blood of the intended recipient or suspending or thickening agents.

Examples of suitable aqueous and nonaqueous carriers that may be employed in the pharmaceutical compositions of the invention include water, ethanol, polyols (such as glycerol, propylene glycol, polyethylene glycol, and the like), and suitable mixtures thereof, vegetable oils, such as olive oil, and injectable organic esters, such as ethyl oleate. Proper fluidity can be maintained, for example, by the use of coating materials, such as lecithin, by the maintenance of the required particle size in the case of dispersions, and by the use of surfactants.

These compositions may also contain adjuvants such as preservatives, wetting agents, emulsifying agents and dispersing agents. Prevention of the action of microorganisms may be ensured by the inclusion of various antibacterial and antifungal agents, for example, paraben, chlorobutanol, phenol sorbic acid, and the like. It may also be desirable to include isotonic agents, such as sugars, sodium chloride, and the like into the compositions. In addition, prolonged absorption of the injectable pharmaceutical form may be brought about by the inclusion of agents that delay absorption such as aluminum monostearate and gelatin.

In some cases, in order to prolong the effect of a drug, it is desirable to slow the absorption of the drug from subcutaneous or intramuscular injection. This may be accomplished by the use of a liquid suspension of crystalline or amorphous material having poor water solubility. The rate of absorption of the drug then depends upon its rate of dissolution, which, in turn, may depend upon crystal size and crystalline form. Alternatively, delayed absorption of a parenterally administered drug form is accomplished by dissolving or suspending the drug in an oil vehicle.

Injectable depot forms are made by forming microencapsulated matrices of the subject compounds in biodegradable polymers such as polylactide-polyglycolide. Depending on the ratio of drug to polymer, and the nature of the particular polymer employed, the rate of drug release can be controlled. Examples of other biodegradable polymers include poly(orthoesters) and poly(anhydrides). Depot injectable formulations are also prepared by entrapping the drug in liposomes or microemulsions that are compatible with body tissue.

For use in the methods of this invention, active compounds can be given per se or as a pharmaceutical composition containing, for example, 0.1 to 99.5% (more preferably, 0.5 to 90%) of active ingredient in combination with a pharmaceutically acceptable carrier.

Methods of introduction may also be provided by rechargeable or biodegradable devices. Various slow release polymeric devices have been developed and tested in vivo in recent years for the controlled delivery of drugs, including proteinacious biopharmaceuticals. A variety of biocompatible polymers (including hydrogels), including both biodegradable and non-degradable polymers, can be used to form an implant for the sustained release of a compound at a particular target site.

Actual dosage levels of the active ingredients in the pharmaceutical compositions may be varied so as to obtain an amount of the active ingredient that is effective to achieve the desired therapeutic response for a particular patient, composition, and mode of administration, without being toxic to the patient.

The selected dosage level will depend upon a variety of factors including the activity of the particular compound or combination of compounds employed, or the ester, salt or amide thereof, the route of administration, the time of administration, the rate of excretion of the particular compound(s) being employed, the duration of the treatment, other drugs, compounds and/or materials used in combination with the particular compound(s) employed, the age, sex, weight, condition, general health and prior medical history of the subject being treated, and like factors well known in the medical arts.

A physician or veterinarian having ordinary skill in the art can readily determine and prescribe the therapeutically effective amount of the pharmaceutical composition required. For example, the physician or veterinarian could start doses of the pharmaceutical composition or compound at levels lower than that required in order to achieve the desired therapeutic effect and gradually increase the dosage until the desired effect is achieved. By “therapeutically effective amount” is meant the concentration of a compound that is sufficient to elicit the desired therapeutic effect. It is generally understood that the effective amount of the compound will vary according to the weight, sex, age, and medical history of the subject. Other factors which influence the effective amount may include, but are not limited to, the severity of the subject's condition, the disorder being treated, the stability of the compound, and, if desired, another type of therapeutic agent being administered with the compound of the invention. A larger total dose can be delivered by multiple administrations of the agent. Methods to determine efficacy and dosage are known to those skilled in the art (Isselbacher et al. (1996) Harrison's Principles of Internal Medicine 13 ed., 1814-1882, herein incorporated by reference).

In general, a suitable daily dose of an active compound used in the compositions and methods of the invention will be that amount of the compound that is the lowest dose effective to produce a therapeutic effect. Such an effective dose will generally depend upon the factors described above.

If desired, the effective daily dose of the active compound may be administered as one, two, three, four, five, six or more sub-doses administered separately at appropriate intervals throughout the day, optionally, in unit dosage forms. In certain embodiments of the present invention, the active compound may be administered two or three times daily. In preferred embodiments, the active compound will be administered once daily.

In certain embodiments, the dosing follows a 3+3 design. The traditional 3+3 design requires no modeling of the dose-toxicity curve beyond the classical assumption for cytotoxic drugs that toxicity increases with dose. This rule-based design proceeds with cohorts of three patients; the first cohort is treated at a starting dose that is considered to be safe based on extrapolation from animal toxicological data, and the subsequent cohorts are treated at increasing dose levels that have been fixed in advance. In some embodiments, the three doses of a compound of formula (I) range from about 100 mg to about 1000 mg orally, such as about 200 mg to about 800 mg, such as about 400 mg to about 700 mg, such as about 100 mg to about 400 mg, such as about 500 mg to about 1000 mg, and further such as about 500 mg to about 600 mg. Dosing can be three times a day when taken with without food, or twice a day when taken with food. In certain embodiments, the three doses of a compound of formula (I) range from about 400 mg to about 800 mg, such as about 400 mg to about 700 mg, such as about 500 mg to about 800 mg, and further such as about 500 mg to about 600 mg twice a day. In certain preferred embodiments, a dose of greater than about 600 mg is dosed twice a day.

If none of the three patients in a cohort experiences a dose-limiting toxicity, another three patients will be treated at the next higher dose level. However, if one of the first three patients experiences a dose-limiting toxicity, three more patients will be treated at the same dose level. The dose escalation continues until at least two patients among a cohort of three to six patients experience dose-limiting toxicities (i.e., ≥about 33% of patients with a dose-limiting toxicity at that dose level). The recommended dose for phase II trials is conventionally defined as the dose level just below this toxic dose level.

In certain embodiments, the dosing schedule can be about 40 mg/m² to about 100 mg/m², such as about 50 mg/m² to about 80 mg/m², and further such as about 70 mg/m² to about 90 mg/m² by IV for 3 weeks of a 4 week cycle.

In certain embodiments, compounds of the invention may be used alone or conjointly administered with another type of therapeutic agent. As used herein, the phrase “conjoint administration” refers to any form of administration of two or more different therapeutic compounds such that the second compound is administered while the previously administered therapeutic compound is still effective in the body (e.g., the two compounds are simultaneously effective in the subject, which may include synergistic effects of the two compounds). For example, the different therapeutic compounds can be administered either in the same formulation or in a separate formulation, either concomitantly or sequentially. In certain embodiments, the different therapeutic compounds can be administered within one hour, 12 hours, 24 hours, 36 hours, 48 hours, 72 hours, or a week of one another. Thus, a subject who receives such treatment can benefit from a combined effect of different therapeutic compounds.

In certain embodiments, conjoint administration of compounds of the invention with one or more additional therapeutic agent(s) (e.g., one or more additional chemotherapeutic agent(s)) provides improved efficacy relative to each individual administration of the compound of the invention (e.g., compound of formula I or Ia) or the one or more additional therapeutic agent(s). In certain such embodiments, the conjoint administration provides an additive effect, wherein an additive effect refers to the sum of each of the effects of individual administration of the compound of the invention and the one or more additional therapeutic agent(s).

This invention includes the use of pharmaceutically acceptable salts of compounds of the invention in the compositions and methods of the present invention. In certain embodiments, contemplated salts of the invention include, but are not limited to, alkyl, dialkyl, trialkyl or tetra-alkyl ammonium salts. In certain embodiments, contemplated salts of the invention include, but are not limited to, L-arginine, benenthamine, benzathine, betaine, calcium hydroxide, choline, deanol, diethanolamine, diethylamine, 2-(diethylamino)ethanol, ethanolamine, ethylenediamine, N-methylglucamine, hydrabamine, 1H-imidazole, lithium, L-lysine, magnesium, 4-(2-hydroxyethyl)morpholine, piperazine, potassium, 1-(2-hydroxyethyl)pyrrolidine, sodium, triethanolamine, tromethamine, and zinc salts. In certain embodiments, contemplated salts of the invention include, but are not limited to, Na, Ca, K, Mg, Zn or other metal salts.

The pharmaceutically acceptable acid addition salts can also exist as various solvates, such as with water, methanol, ethanol, dimethylformamide, and the like. Mixtures of such solvates can also be prepared. The source of such solvate can be from the solvent of crystallization, inherent in the solvent of preparation or crystallization, or adventitious to such solvent.

Wetting agents, emulsifiers and lubricants, such as sodium lauryl sulfate and magnesium stearate, as well as coloring agents, release agents, coating agents, sweetening, flavoring and perfuming agents, preservatives and antioxidants can also be present in the compositions.

Examples of pharmaceutically acceptable antioxidants include: (1) water-soluble antioxidants, such as ascorbic acid, cysteine hydrochloride, sodium bisulfate, sodium metabisulfite, sodium sulfite and the like; (2) oil-soluble antioxidants, such as ascorbyl palmitate, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), lecithin, propyl gallate, alpha-tocopherol, and the like; and (3) metal-chelating agents, such as citric acid, ethylenediamine tetraacetic acid (EDTA), sorbitol, tartaric acid, phosphoric acid, and the like.

The invention now being generally described, it will be more readily understood by reference to the following examples which are included merely for purposes of illustration of certain aspects and embodiments of the present invention, and are not intended to limit the invention.

General Synthetic Procedures

Compound numbers 1-129 as used in the general synthesis section below refer only to genus structures in this section and do not apply to compounds disclosed elsewhere in this application. Compounds disclosed herein can be made by methods depicted in the reaction schemes below.

The starting materials and reagents used in preparing these compounds are either available from commercial supplier such as Aldrich Chemical Co., Bachem, etc., or can be made by methods well known in the art. The schemes are merely illustrative of some methods by which the compounds disclosed herein can be synthesized and various modifications to these schemes can be made and will be suggested to POSITA having referred to this disclosure. The starting materials and the intermediates and the final products of the reaction may be isolated and purified if desired using conventional techniques, including but not limited to filtration, distillation, crystallization, chromatography, and the like and may be characterized using conventional means, including physical constants and spectral data.

Unless specified otherwise, the reactions described herein take place at atmospheric pressure over a temperature range from about −78° C. to about 150° C.

General Schemes

Compounds of Formula (I) having the structure:

where Z, R^(u), R^(v), R^(w), R^(x), R⁵, and R⁹ are analogous to variables Z, R^(a), R^(b), R^(w), R⁵, R⁹ and R^(x) is —CH₂P(O)(OR¹⁵)₂ or —OP(O)(OH)CH₂P(O)(OR¹⁵)₂ as defined in the Summary, can be synthesized as illustrated and described in Scheme 1:

Ketone A-3 is prepared from commercially available diol A-1 via selective protecting the primary alcohol with a suitable group such as TBDPS, TBDMS, Ac and Bz, and followed by oxidizing the secondary alcohol in A-2 where R″ is H, alkyl, TMS, or heterocycles. Stereoselective addition of the corresponding ethynyl nucleophile A-4, such as Grignard reagents or Li reagents, to ketone A-3 to provide propargylic alcohol A-5. Removal of the acetonide protecting group is accomplished with diluted aq. acid, such as TFA, HCl, H₂SO₄, HClO₄, PPTS, CSA or other Lewis acids. Acylation of triol A-6 with reagents, such as Ac₂O, acetyl chloride, and BzCl, in the presence of a base, such as pyridine, and catalytic 4-DMAP to provide tri-ester such as ti-acetate A-7. Glycosylation under conditions (N,O-bis(trimethylsilyl)-acetamide and TMSOTf) or (TfOH and DBU) in solvent (MeCN, dichloroethane or toluene), between donor A-7 and acceptor A-8, such as 2-chloroadenine, 6-amino-2-chloroadenine, 2,6-dichloroadenine, 5,7-dichloro-1H-imidazo[4,5-b]pyridine, 5-chloro-3H-imidazo[4,5-b]pyridine, uracil, thymine, cytosine or guanine, to provide the nucleoside product A-9. In the case when R^(u) is NH₂, it is protected as N(Boc)₂ with Boc₂O in the presence of TEA and catalytic 4-DMAP. Removal of the protecting group in A-9, in the case of P is TBDMS or TBDPS group, treatment with TBAF to give the primary alcohol A-10 which then is undergone an insertion reaction with diazo reagent A-11 in the presence of catalyst such as Rh₂(OAc)₄ or Cu(OAc)₂ to provide A-12. Alkylation with an electrophile A-13 such as alkyl halide, triflate, tosylate or mesylate in the presence of base such as Cs₂CO₃, K₂CO₃, LiHMDS, DBU or NaH, to provide A-14. The ester groups in A-14 is finally removed by base such as LiOH, NaOH, and KOH in water to provide A-15 in formula (Ia).

Alternatively, the alkynyl group at the 3′-position in intermediate A-5 can be substituted with either alkyl or vinyl groups by using the corresponding alkyl or vinyl lithium and Grignard reagents at Step 3 in Scheme 1.

Compounds in formula (Ia) can also be prepared according to Scheme 2. The suitable protecting group such as P is a silyl group (TBDPS or TBDMS) in precursor B-1 can be selectively removed by reagent such as TBAF or HF in THF while the P¹ protecting group such as Ac, Bz and MOM group remains. The resulting primary alcohol B-2 can react with diazo reagent A-11 in solvent such as benzene, toluene, DCM and dichloroethane in the presence of metal catalyst such as Rh₂(OAc)₄ to give intermediate B-3. Alkylation of B-3 with electrophile A-13 such as halide, triflate, mesylate or sulfonate is accomplished in the presence of a base such as K₂CO₃, Cs₂CO₃, LiHMDS, NaH and DBU to give intermediate B-4. Removing the acetonide protecting group in B-4 is done by an acid treatment such as aq. TFA, HCl, H₂SO₄ or HClO₄ in solvent such as DCM, acetone, THF or dioxane to provide diol B-5. Acylation of B-5 with reagent such as Ac₂O or acetyl chloride in the presence of pyridine, TEA or DIPEA and catalytic 4-DMAP to give ti-acetate B-6 (for P¹═OAc) as a glycosylation donor. This intermediate B-6 is reacted with a glycosylation acceptor heterocycle B-7 such as 2-chloroadenine, 6-amino-2-chloroadenine, 2,6-dichloroadenine, 5,7-dichloro-1H-imidazo[4,5-b]pyridine, 5-chloro-3H-imidazo[4,5-b]pyridine, uracil, thymine, cytosine and guanine under the influence of conditions such as [N,O-bis(trimethylsilyl)-acetamide and TMSOTf] or (TfOH and DBU) in solvent (MeCN, dichloroethane or DME) to provide nucleoside intermediate B-8. Finally removal of the ester protecting groups in B-8 with the treatment of aq. LiOH, NaOH, and KOH in solvent such as THF, dioxane, MeOH or EtOH to provide the desired final product in the formula (Ia).

Compounds in formula (Ia) can also be prepared according to Scheme 3. 2,6-Dichloroadenine C-1 prepared according to Scheme 1 can proceed into several synthetic transformations. Selective nucleophilic displacement of the 6-chloro group in precursor 1 with nucleophile R^(u)—H (C-2) such as amines, alkoxides or thiolates in solvent such as DMF, THF, dioxane, alcohols or NMP to provide intermediate C-3. Precursor C-1 also can undergo a coupling reaction such as Suzuki, Stille or Negishi reaction with the corresponding reagent such as boronic acids (C-4), boronic esters, Tin reagents (C-5) or Zinc reagents (C-6) to provide intermediate C-7, respectively. Treatment of both intermediates C-3 and C-7 with aq. LiOH, NaOH, KOH, NaOMe, NaOEt or KOEt in solvent such as THF, dioxane, MeOH or EtOH to provide the desired final products in the formula (Ia).

Compounds in formula (Ia) can also be prepared via C-1 according to Scheme 4. In this method, treatment of A-7 with 2,6-dichloropurine, TMSOTf and N,O-bis(trimethylsilyl)acetamide via the Vorbrüggen reaction gives protected nucleoside D-2. Selective removal of the tert-butyldiphenylsilyl moiety from the 5′-hydroxyl group gives alcohol D-3. Coupling with a desired substituted acyldiazo-reagent D-4 gives substituted nucleoside D-5. A wide variety of diazo reagents can be used in this reaction. Some examples include those where R^(w) is CO₂R⁹, SOR⁹, SO₂R⁹, P(O)(OR⁹)₂, and CN and R⁹ is defined as in the Summary. If an alkyl substituent R⁵ is desired, it can be conveniently introduced using an alkylation reaction where a nucleophile such as R⁵—X (X=halide, OTf, OMs or OTs) is used with a base like cesium carbonate in a polar aprotic solvent like THF or DMF to give key intermediate C-1. A substituent such as an amine can be added to the purine base by displacing the chlorine at the 6-position to give intermediate D-7 with variety of amines D-6 in a solvent such as EtOH, THF or dioxane. Final deprotection of D-7 by using an aqueous hydrolysis with a base such as lithium hydroxide gives target compound in the structure of formula (1).

Compounds in formula (Ia) can also be prepared according to Scheme 5. Alkylation of precursor B-3 from Scheme 2 above with an electrophile E-1 such as 4-iodobenzyl halide (Br, Cl, or I) or the corresponding OTf, OMs or OTs with base such as K₂CO₃, Cs₂CO₃, NaH or LiHMDS in solvent like DMF or THF leads to intermediate E-2 which can couple with various boronic acids such as (2-oxo-1,2-dihydropyridin-3-yl)boronic acid (E-3) illustrated here. The resulting pyridone product E-4 is alkylated with various alkyl halides (A-13) in the presence of base such as K₂CO₃, Cs₂CO₃, NaH or LiHMDS in solvent like DMF and THF to give E-5. The acetonide protecting group in E-5 is removed with the treatment of aq. TFA, HCl, H₂SO₄ or AcOH in a solvent such as DCM, acetone, dioxane or THF to give diol E-6 which is acetylated with Ac₂O or acetyl chloride with a catalytic amount of 4-DMAP and a base such as pyridine, TEA or DIPEA in solvent like DCM to provide an anomeric mixture E-7 as a glycosylation donor. Intermediate E-7 can either react with heterocyclic acceptor 2,6-dichloroadenine (D-1) or N-substituted 6-amino-2-chloroadenine (E-9) which is formed from displacing the 6-chloro group in D-1 with the suitable amines (D-7). Both glycosylation can be done under the activation conditions such as [(N,O-bis(trimethylsilyl)-acetamide and TMSOTf] or (TfOH and DBU) in solvent (MeCN, dichloroethane or toluene), between donor E-7 and acceptors D-1 or E-9 to provide the corresponding nucleoside products, E-8 or E-10 respectively. Nucleoside E-8 is converted into E-10 via a nucleophilic displacement with various amines (D-7). Finally, desired compounds in formula (Ia) is produced from E-10 via the deprotection of all its ester groups with treatment of aq. LiOH, NaOH, and KOH in a solvent such as THF, dioxane, MeOH or EtOH.

Compounds in formula (Ia) can also be prepared according to Scheme 6. Alkylation with benzyl halide F-4 with various alkyl side chains (R⁵) and precursor B-3 in the presence of base such as K₂CO₃, Cs₂CO₃, LiHMDS or NaH in suitable solvent like DMF or THF leads to intermediate F-5. Triacetate F-7 is formed via a two-step transformation from F-5 via a deprotection (aq. TFA in DCM) and acylation (Ac₂O or acetyl chloride in pyridine) as described aforementioned schemes. Glycosylation between F-7 and various acceptors such as 2,6-dichloroadenine (D-1) under an activation conditions [(N,O-bis(trimethylsilyl)-acetamide and TMSOTf] or (TfOH and DBU) in solvent (MeCN, dichloroethane or toluene) to provide nucleoside F-8 which is converted to amino analogs F-10 with various amines (F-9) in the presence of base such as pyridine, TEA or DIPEA in appropriate solvent like dioxane, DMF, or THF. Finally, desired molecules in formula (1) is obtained from F-10 with the treatment of aq. LiOH, NaOH, and KOH in a solvent such as THF, dioxane, MeOH or EtOH. Alternatively, intermediate F-10 can also directly produced from glycosylation between donor F-7 and other acceptors such as N-substituted 6-amino-2-chloroadenines (F-11).

The required benzyl halides F-4 is prepared from 4-(((tert-butyldimethylsilyl)oxy)-methyl)aniline (F-1) via a five-step transformation. The cyclic urea ring is initially formed from aniline F-1 reacting with 3-chloropropyl isocyanate and followed by cyclization under the influence of a base such as NaH, NaOH or LiHMDS in solvent like DMF or THF to generate F-2. Intermediate F-2 is then led to F-3 by removal of the TBDMS group with TBAF and proceeds to the final product by converting the primary alcohol to the bromide with CBr₄ and PPh₃ in solvent such as DCM or THF.

Alternatively, key intermediate F-5 is also prepared from precursor B-3 according to Scheme 7. Alkylation of precursor B-3 with halides such as 4-nitrobenzyl bromide in the presence of base such K₂CO₃ or Cs₂CO₃ in DMF to provide the nitro intermediate which is then reduced to the aniline with Fe in aq. NH₄Cl. Cyclic urea formation is carried out from aniline with 3-chloropropyl isocyanate in the presence of base such as TEA in THF and followed by intramolecular ring closure with the treatment of base such as NaH or LiHMDS. Introduction of the N-alkyl side chains is accomplished with electrophile such as A-13 to provide key intermediate F-5.

Formula (Ib) can be prepared according to Scheme 8. The required diazo reagent G-2 which R^(w) is an aryl or heteroaryl group, can be prepared from ester G-1 with the suitable sulfonyl azide reagent, such as 4-acetmidobenzenesulfonyl azide in the presence of a base, such as Et₃N and DBU, in MeCN or dioxane. Coupling of diazo reagent G-2 and alcohol A-9 from Scheme 1 via the insertion reaction catalyzed by Rh or Cu catalyst such as Rh₂(OAc)₄, in a solvent such as toluene, DCM or dichloroethane to give product G-3. Alkylation of G-3 with an electrophile A-13 such as alkyl halide, triflate, tosylate or mesylate in the presence of base such as Cs₂CO₃, K₂CO₃, LiHMDS, DBU or NaH, to provide G-4. The ester groups in G-4 is finally removed by an aq. base such as LiOH, NaOH, and KOH to provide the desired product in formula (Ib).

Compounds in formula (Ib) can also be prepared according to Scheme 9. The primary alcohol B-2 can react with diazo reagent G-2 from Scheme 8 in the presence of a metal catalyst such as Rh₂(OAc)₄ in a solvent such as benzene, toluene, DCM or dichloroethane to give intermediate H-1. Alkylation of H-1 with an electrophile A-13 such as halide, triflate, mesylate or sulfonate is accomplished in the presence of base such as K₂CO₃, Cs₂CO₃, LiHMDS, NaH and DBU to give intermediate H-2. Removing the acetonide protecting group in H-2 is done by acid treatment such as aq. TFA, HCl, H₂SO₄, HClO₄ or CSA in solvent such as DCM, acetone, THF or dioxane to provide diol H-3. Acylation of H-3 with a reagent such as Ac₂O or acetyl chloride in the presence of pyridine, TEA or DIPEA and catalytic 4-DMAP to give ti-acetate H-4 as a glycosylation donor. This intermediate H-4 is reacted with a glycosylation acceptor heterocycle B-7 such as 2-chloroadenine, 6-amino-2-chloroadenine, 2,6-dichloroadenine, 5,7-dichloro-1H-imidazo[4,5-b]pyridine, 5-chloro-3H-imidazo[4,5-b]pyridine, uracil, thymine, cytosine and guanine under the conditions such as [N,O-bis(trimethylsilyl)-acetamide and TMSOTf] or (TfOH and DBU) in a solvent (MeCN, dichloroethane or DME) to provide nucleoside intermediate H-5. Finally removal of the ester protecting groups in H-5 with the treatment of aq. LiOH, NaOH, and KOH in a solvent such as THF, dioxane, MeOH or EtOH to provide the desired final product in the formula (Ib).

Compounds in formula (Ic) can also be prepared according to Scheme 10. Tertiary alcohol I-2 where R¹ is methyl (prepared according to the procedure reported by Franchetti, P. et al. J. Med. Chem. 2005, 48, 4983-4989) or other alkyl groups; ethynyl (prepared according to the procedure by Hulpia, F. et al. Bioorg. Med. Chem. Lett. 2016, 26, 1970-1972) or other alkynyl groups; and vinyl groups, was converted into I-4 either directly by treatment of acetylation reagent such as Ac₂O and catalytic amount of H₂SO₄ in AcOH or via a 2-step process involving deprotection of the acetonide group with treatment of aq. TFA or other acid in DCM first and followed by acetylation of the resulting diol I-3 with a reagent such as Ac₂O or acetyl chloride. Glycosylation of I-4 with a heteroaromatic glycosyl acceptor such as heterocycle B-7 described in Scheme 2 where R^(u) is H, Cl, NH₂, N-alkyl group such as 2-chloroadenine, 6-amino-2-chloroadenine, 2,6-dichloroadenine, 5,7-dichloro-1H-imidazo[4,5-b]pyridine, 5-chloro-3H-imidazo[4,5-b]pyridine, uracil, thymine, cytosine and guanine under the conditions such as [N,O-bis(trimethylsilyl)-acetamide and TMSOTf] or (TfOH and DBU) in a solvent (MeCN, dichloroethane or DME) to provide nucleoside intermediate I-5. Removal of the silyl protecting group in I-5 with a source of fluoride such as TBAF in THF to give primary alcohol I-6 which was further converted into triol I-7 with aq. LiOH or NaOH in solvent such as THF, MeOH or EtOH. Finally, treatment of I-7 with methylenebis(phosphonic dichloride) and trimethylphosphate before it is followed by triethylammonium carbonate to provide the desired final product in the formula (Ic).

Compounds in formula (Ic) can be prepared according to Scheme 11. Primary alcohol I-6 (where R^(u)═C₁) is alkylated with electrophile J-1 such as (diethoxyphosphoryl)methyl trifluoromethanesulfonate or diethyl (iodomethyl)phosphonate in the presence of a base, such as TEA, DIPEA, NaH and Cs₂CO₃ in a solvent such as THF, DMF, dioxane or NMP to give intermediate J-2. Installation of the amino group in J-4 via nucleophilic displacement of the chloro group in J-2 with R⁷R₈NH (J-3) where R⁷ and R⁸ are H or alkyl groups, in the presence of a base such as TEA or DIPEA in solvent such as dioxane, THF, or DMF. A two-step deprotection sequence (TMSBr and aq. LiOH or NaOH) is required to convert J-4 to the desired product in formula (Ic).

Those having skill in the art will recognize that the starting materials and reaction conditions may be varied, the sequence of the reactions altered, and additional steps employed to produce compounds encompassed by the present invention, as demonstrated by the following examples. In some cases, protection of certain reactive functionalities may be necessary to achieve some of the above transformations. In general, the need for such protecting groups as well as the conditions necessary to attach and remove such groups will be apparent to experienced organic chemists. The disclosures of all articles and references mentioned in this application, including patents, are incorporated herein by reference.

The preparation of the compounds of the present invention is illustrated further by the following examples, which are not to be construed as limiting the invention in scope or spirit to the specific procedures and compounds described in them.

SYNTHETIC EXAMPLES Example 1 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-benzylmalonic acid

Step 1:

To a mixture of (3aR,5R,6aS)-5-(((tert-butyldiphenylsilyl)oxy)methyl)-2,2-dimethyldihydrofuro[2,3-d][1,3]dioxol-6 (3aH)-one (10 g, 23.44 mmol, 1 eq) in THF (100 mL) was added ethynylmagnesium bromide (0.5 M, 328.19 mL, 7 eq) at 15° C. under N₂ atmosphere. The mixture was stirred for 16 h before additional ethynylmagnesium bromide (0.5 M, 125 mL, 3 eq) was added. The mixture was stirred further for 3 h before it was diluted with saturated aq. NH₄Cl (250 mL) and extracted with EtOAc (3×250 mL). The combined organic layer was washed with brine (250 mL), dried over Na₂SO₄, filtered and concentrated to dryness. The crude product was purified by flash silica gel column chromatography (petroleum ether:EtOAc=1:0-4:1) to provide (3aR,5R,6R,6aR)-5-(((tert-butyldiphenylsilyl)oxy)methyl)-6-ethynyl-2,2-dimethyl-tetrahydrofuro[2,3-d][1,3]dioxol-6-ol (19.47 g, 92% yield) as a yellow solid.

Step 2:

To a solution of (3aR,5R,6R,6aR)-5-(((tert-butyldiphenylsilyl)oxy)methyl)-6-ethynyl-2,2-dimethyltetrahydrofuro[2,3-d][1,3]dioxol-6-ol (9.47 g, 20.92 mmol, 1 eq) in DCM (100 mL) was added H₂O (10 mL) and TFA (100 mL) at 0° C. The mixture was stirred at 25° C. for 1 h before it was quenched with saturated aq. NaHCO₃ to pH 7 and then extracted with DCM (2×300 mL). The combined organic layer was washed with brine (200 mL), dried over Na₂SO₄, filtered and concentrated to dryness. The crude product was purified by flash silica gel column chromatography (petroleum ether:EtOAc=1:0-0:1) to provide (3R,4S,5R)-5-(((tert-butyldiphenylsilyl)oxy)methyl)-4-ethynyltetrahydro-furan-2,3,4-triol (5.17 g, 60% yield) as a yellow gum.

Step 3:

To a solution of (3R,4S,5R)-5-(((tert-butyldiphenylsilyl)oxy)methyl)-4-ethynyltetra-hydrofuran-2,3,4-triol (5.17 g, 12.53 mmol, 1 eq) in pyridine (50 mL) at 15° C. was added 4-DMAP (4.59 g, 37.60 mmol, 3 eq) and Ac₂O (11.74 mL, 125.32 mmol, 10 eq). The mixture was stirred at 15° C. for 16 h before H₂O (500 mL) was added to the mixture. The reaction mixture was extracted with EtOAc (3×200 mL). The combined organic layer was washed with brine (200 mL), dried over Na₂SO₄, filtered and concentrated to dryness. The crude product was purified by flash silica gel column chromatography (petroleum ether:EtOAc=1:0-1:1) to provide (3R,4R,5R)-5-(((tert-butyldiphenylsilyl)oxy)methyl)-4-ethynyltetra-hydrofuran-2,3,4-triyl triacetate (7.19 g, 79% yield) as a yellow gum.

Step 4:

To a solution of (3R,4R,5R)-5-(((tert-butyldiphenylsilyl)oxy)methyl)-4-ethynyltetra-hydrofuran-2,3,4-triyl triacetate (6.89 g, 12.79 mmol, 1 eq) in MeCN (5 mL) at 0° C. was added 2-chloroadenine (2.39 g, 14.07 mmol, 1.1 eq), DBU (5.78 mL, 38.37 mmol, 3 eq) and TMSOTf (11.56 mL, 63.96 mmol, 5 eq). The mixture was stirred at 0° C. for 0.5 h and then stirred at 65° C. for 1 h before it was diluted with saturated aq. NaHCO₃ solution (500 mL). The aqueous phase was extracted with EtOAc (2×350 mL). The combined organic layer was washed with brine (350 mL), dried over Na₂SO₄, filtered and concentrated to dryness. The crude product was purified by flash silica gel column chromatography (petroleum ether:EtOAc=1:0-0:1) to provide (2R,3R,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-2-(((tert-butyldiphenylsilyl)oxy)methyl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate (4.52 g, 44% yield) as a yellow solid.

Step 5:

To a solution of (2R,3R,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-2-(((tert-butyldiphenylsilyl)oxy)methyl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate (4.5 g, 6.94 mmol, 1 eq) in DMF (50 mL) at 20° C. was added TEA (4.83 mL, 34.71 mmol, 5 eq), 4-DMAP (254 mg, 2.08 mmol, 0.3 eq) and Boc₂O (7.58 g, 34.71 mmol, 5 eq). The mixture was stirred at 20° C. for 1 h before H₂O (250 mL) was added to the mixture. The reaction mixture was extracted with EtOAc (3×230 mL). The combined organic layer was washed with brine (250 mL), dried over Na₂SO₄, filtered and concentrated. The crude product was purified by flash silica gel column chromatography (petroleum ether:EtOAc=1:0-1:1) to provide (2R,3R,4R,5R)-5-(6-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-2-(((tert-butyldiphenylsilyl)oxy)methyl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate (3.26 g, 46% yield) as a yellow foam.

Step 6:

To a solution of (2R,3R,4R,5R)-5-(6-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-2-(((tert-butyldiphenylsilyl)oxy)methyl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate (3.24 g, 3.82 mmol, 1 eq) in THF (35 mL) at 0° C. was added TBAF (1 M, 5.73 mL, 1.5 eq). The reaction mixture was stirred at 0° C. for 1 h before it was diluted with H₂O (150 mL). The reaction mixture was extracted with EtOAc (3×130 mL). The combined organic layer was washed with brine (150 mL), dried over Na₂SO₄, filtered and concentrated. The crude product was purified by flash silica gel column chromatography (petroleum ether:EtOAc=1:0-1:2) to provide (2R,3R,4R,5R)-5-(6-N,N′-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyl-2-(hydroxymethyl)tetrahydrofuran-3,4-diyl diacetate (1.51 g, 54% yield) as a yellow foam.

Step 7:

To a solution of (2R,3R,4R,5R)-5-(6-N,N′-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyl-2-(hydroxymethyl)tetrahydrofuran-3,4-diyl diacetate (1.48 g, 2.43 mmol, 1 eq) in toluene (10 mL) at 20° C. under N₂ atmosphere was added Rh₂(OAc)₄ (214 mg, 485.24 umol, 0.2 eq) and diethyl diazomalonate (903 mg, 4.85 mmol, 2 eq) in toluene (3 mL). The mixture was stirred at 95° C. for 2 h to give a green suspension before it was cooled to room temperature and concentrated to dryness. The crude product was purified by flash silica gel column chromatography (petroleum ether:EtOAc=1:0-3:1) to provide diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-N,N′-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (517 mg, 20% yield) as a yellow foam.

Step 8:

To a solution of diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-N,N′-(bis-(tert-butoxy-carbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (497.00 mg, 647.00 umol, 1 eq) in DMF (5 mL) at 25° C. was added K₂CO₃ (178.84 mg, 1.29 mmol, 2 eq). The reaction mixture was stirred for 30 min and followed by addition of benzyl bromide (221.32 mg, 1.29 mmol, 153.69 uL, 2 eq). The mixture was stirred at 25° C. for 15.5 h before additional K₂CO₃ (100 mg) and BnBr (100 uL) were added to the mixture. The resulting mixture was stirred at 25° C. for 24 h before H₂O (50 mL) was added to the reaction.

The reaction mixture was extracted with EtOAc (2×50 mL). The combined organic layer was washed with brine (50 mL), dried over Na₂SO₄, filtered and concentrated. The crude product was purified by flash silica gel column chromatography (petroleum ether:EtOAc=1:0-3:1) to provide diethyl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-malonate (266 mg, 37% yield) as a yellow foam.

Step 9:

To a solution of diethyl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-malonate (266 mg, 309.92 umol, 1 eq) in DCM (3 mL) was added TFA (0.45 mL) at 0° C.

The mixture was stirred at 25° C. for 16 h before it was treated with saturated aq. NaHCO₃ solution to pH 7. The reaction mixture was extracted with DCM (2×50 mL). The combined organic layer was washed with brine (50 mL), dried over Na₂SO₄, filtered and concentrated to provide crude diethyl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (195 mg) as a yellow foam.

Step 10:

The mixture of crude diethyl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (195 mg, 296.33 umol, 1 eq) in saturated NH₃ in MeOH (3 mL) was stirred at 10° C. for 16 h before it was concentrated to dryness directly. The crude product was purified by preparative TLC (EtOAc) to provide diethyl 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-benzylmalonate (91.7 mg, 49% yield) as a yellow foam.

Step 11:

To a solution of diethyl 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-benzylmalonate (81 mg, 141.12 umol, 1 eq) in EtOH (2 mL) was added LiOH·H₂O (30 mg, 705.60 umol, 5 eq) in H₂O (0.2 mL) at 10° C. The mixture was stirred at 50° C. for 4 h before it was concentrated to dryness. The residue was dissolved in H₂O (50 ml) and extracted with EtOAc (2×50 mL). The organic layers were discarded and the aqueous phase was acidified to pH˜2.5 with 1N aq. HCl solution. The aqueous phase was extracted with EtOAc (3×50 mL). The combined organic layer was washed with brine (50 mL), dried over Na₂SO₄, filtered and concentrated to provide the title compound (55.4 mg, 74% yield) as a white solid.

¹H NMR (400 MHz, DMSO-d₆) δ ppm 8.39 (s, 1H), 7.79 (br s, 2H), 7.20 (br d, J=7.03 Hz, 2H), 7.01-7.12 (m, 3H), 5.82 (d, J=7.53 Hz, 1H), 4.87 (d, J=7.78 Hz, 1H), 4.16 (dd, J=5.27, 2.51 Hz, 1H), 3.99-4.07 (m, 2H), 3.83 (br d, J=8.03 Hz, 1H), 3.56 (s, 1H), 3.25 (dd, J=6.78 Hz, 2H); LC/MS [M+H]=518.0.

Example 2 Synthesis of 2-(((2S,3R,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-4-hydroxytetrahydrofuran-2-yl)methoxy)-2-benzylmalonic acid

Step 1:

To a solution of (2R,3R,4R,5R)-5-(6-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-2-(((tert-butyldiphenylsilyl)oxy)methyl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate (5 g, 5.89 mmol, 1 eq) was added 2M NH₃ in MeOH (50 mL) at 0° C. The reaction mixture was stirred at 25° C. for 16 h before it was concentrated. The crude was purified by flash silica gel column chromatography (0-50% EtOAc in petroleum ether) to provide tert-butyl (9-((2R,3R,4S,5R)-5-(((tert-butyldiphenylsilyl)oxy)methyl)-4-ethynyl-3,4-dihydroxy-tetrahydrofuran-2-yl)-2-chloro-9H-purin-6-yl)carbamate (3.78 g, 90% yield) as a yellow foam.

Step 2:

To a solution of tert-butyl (9-((2R,3R,4S,5R)-5-(((tert-butyldiphenylsilyl)oxy)-methyl)-4-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)-2-chloro-9H-purin-6-yl)carbamate (3.78 g, 5.29 mmol, 1 eq) in DCM (40 mL) at 0° C. under N₂ atmosphere was added 4-DMAP (258.63 mg, 2.12 mmol, 0.4 eq) and TCDI (4.72 g, 26.46 mmol, 5 eq). The reaction mixture was stirred at 25° C. for 16 h before it was concentrated. The crude was purified by flash silica gel column chromatography (0-33% EtOAc in petroleum ether) to provide tert-butyl (9-((3aR,4R,6R,6aR)-6-(((tert-butyldiphenylsilyl)oxy)methyl)-6a-ethynyl-2-thioxotetrahydrofuro[3,4-d][1,3]dioxol-4-yl)-2-chloro-9H-purin-6-yl)carbamate (1.4 g, 37% yield) as a yellow foam.

Step 3:

To a solution of tert-butyl (9-((3aR,4R,6R,6aR)-6-(((tert-butyldiphenylsilyl)oxy)-methyl)-6a-ethynyl-2-thioxotetrahydrofuro[3,4-d][1,3]dioxol-4-yl)-2-chloro-9H-purin-6-yl)carbamate (500 mg, 707.93 umol, 1 eq) in toluene (5 mL) was added AIBN (11.62 mg, 70.79 umol, 0.1 eq) at 20-25° C. The reaction mixture was then heated to 60° C. and followed by addition of (n-Bu)₃SnH (561.96 uL, 2.12 mmol, 3 eq). The reaction mixture was stirred at 60° C. for 1.5 h before it was concentrated. The crude was purified by flash silica gel column chromatography (0-33% EtOAc in petroleum ether) to provide tert-butyl (9-((2R,3R,4R,5S)-5-(((tert-butyldiphenylsilyl)oxy)methyl)-4-ethynyl-3-hydroxytetrahydro-furan-2-yl)-2-chloro-9H-purin-6-yl)carbamate (220 mg, 47% yield) as a white foam.

Step 4:

To a solution of tert-butyl (9-((2R,3R,4R,5S)-5-(((tert-butyldiphenylsilyl)oxy)-methyl)-4-ethynyl-3-hydroxytetrahydrofuran-2-yl)-2-chloro-9H-purin-6-yl)carbamate (220 mg, 339.39 umol, 1 eq) in DCM (1.4 mL) at 0° C. was added TFA (0.7 mL, 9.45 mmol, 28 eq). The reaction mixture was stirred at 25° C. for 1 h before it was diluted with saturated aq. NaHCO₃ solution (15 mL) and extracted with DCM (3×5 mL). The combined organic layer was washed with brine (10 mL), dried over Na₂SO₄, filtered and concentrated to provide crude (2R,3R,4R,5S)-2-(6-amino-2-chloro-9H-purin-9-yl)-5-(((tert-butyldiphenyl-silyl)oxy)methyl)-4-ethynyltetrahydrofuran-3-ol (260 mg) as a yellow foam.

Step 5:

To a solution of (2R,3R,4R,5S)-2-(6-amino-2-chloro-9H-purin-9-yl)-5-(((tert-butyldiphenylsilyl)oxy)methyl)-4-ethynyltetrahydrofuran-3-ol (260 mg, 474.36 umol, 1 eq, crude) in DMF (2.5 mL) was added Boc₂O (931.75 mg, 4.27 mmol, 9 eq), TEA (660.25 uL, 4.74 mmol, 10 eq) and 4-DMAP (5.80 mg, 47.44 umol, 0.1 eq) at 0° C. The reaction mixture was stirred at 25° C. for 1.5 h before it was diluted with H₂O (20 mL) and extracted with EtOAc (3×5 mL). The combined organic layer was washed with brine (10 mL), dried over Na₂SO₄, filtered and concentrated to provide crude (2R,3R,4S,5S)-2-(6-(N,N′-bis-((tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-5-(((tert-butyldiphenylsilyl)oxy)methyl)-4-ethynyltetrahydrofuran-3-yl tert-butyl carbonate (560 mg) as an orange gum.

Step 6:

To a solution of crude (2R,3R,4S,5S)-2-(6-(N,N′-bis-((tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-5-(((tert-butyldiphenylsilyl)oxy)methyl)-4-ethynyltetrahydrofuran-3-yl tert-butyl carbonate (560 mg, 660.02 umol, 1 eq, crude) in THF (6 mL) at 0° C. was added TBAF in THF (1 M, 1 mL, 1.52 eq). The reaction mixture was stirred at 0° C. for 1 h. The reaction mixture was diluted with H₂O (10 mL) and extracted with EtOAc (3×5 mL). The combined organic layer was washed with brine (10 mL), dried over Na₂SO₄, filtered and concentrated. The crude was purified by preparative TLC (petroleum ether:EtOAc=2:1) to provide (2R,3R,4S,5S)-2-(6-(N,N′-bis-((tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-4-ethynyl-5-(hydroxymethyl)tetrahydrofuran-3-yl tert-butyl carbonate (93 mg, 45% yield over 3 steps) as a yellow foam.

Step 7:

To a solution of (2R,3R,4S,5S)-2-(6-(N,N′-bis-((tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-4-ethynyl-5-(hydroxymethyl)tetrahydrofuran-3-yl tert-butyl carbonate (93 mg, 152.45 umol, 1 eq) in toluene (1 mL) at 25° C. under N₂ atmosphere was added Rh₂(OAc)₄ (6.74 mg, 15.24 umol, 0.1 eq). The reaction mixture was heated to 90° C. and followed by addition of diethyl 2-diazomalonate (85.14 mg, 457.34 umol, 3 eq) in toluene (1 mL). The reaction mixture was stirred at 90° C. for 3 h before it was concentrated. The crude residue was purified by flash column chromatography on silica gel to provide diethyl 2-(((2S,3S,4R,5R)-5-(6-(N,N′-bis-((tert-butoxy-carbonyl)amino)-2-chloro-9H-purin-9-yl)-4-((tert-butoxycarbonyl)oxy)-3-ethynyltetrahydro-furan-2-yl)methoxy)malonate (180 mg) as a gum.

Step 8:

To a solution of crude diethyl 2-(((2S,3S,4R,5R)-5-(6-(N,N′-bis-((tert-butoxy-carbonyl)amino)-2-chloro-9H-purin-9-yl)-4-((tert-butoxycarbonyl)oxy)-3-ethynyltetrahydro-furan-2-yl)methoxy)malonate (117.11 mg, 152.45 umol, 1 eq) in DMF (3 mL) was added K₂CO₃ (421.39 mg, 3.05 mmol, 20 eq) at 20-25° C. The reaction mixture was stirred for 0.5 h and followed by addition of benzyl bromide (271.61 uL, 2.29 mmol, 15 eq). The reaction was then stirred further for 16 h before it was diluted with H₂O (20 mL) and extracted with EtOAc (3×10 mL). The combined organic layer was washed with brine (15 mL), dried over Na₂SO₄, filtered and concentrated. The crude was purified by flash silica gel column chromatography (petroleum ether:EtOAc=1:0-2:1 gradient) to provide diethyl 2-(((2S,3S,4R,5R)-5-(6-(N,N′-bis-((tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-4-((tert-butoxycarbonyl)oxy)-3-ethynyltetrahydrofuran-2-yl)methoxy)-2-benzylmalonate (90 mg) as an off-white gum.

Step 9:

To a solution of diethyl 2-(((2S,3S,4R,5R)-5-(6-(N,N′-bis-((tert-butoxycarbonyl)-amino)-2-chloro-9H-purin-9-yl)-4-((tert-butoxycarbonyl)oxy)-3-ethynyltetrahydrofuran-2-yl)methoxy)-2-benzylmalonate (90 mg, 104.86 umol, 1 eq) in DCM (0.6 mL) at 0° C. was added TFA (0.3 mL, 4.05 mmol, 39 eq). The reaction mixture was stirred at 25° C. for 1 h before it was diluted with saturated aq. NaHCO₃ solution (5 mL) and extracted with DCM (3×3 mL). The combined organic layer was washed with brine (5 mL), dried over Na₂SO₄, filtered and concentrated. The crude residue was purified by preparative TLC (petroleum ether:EtOAc=1:1) to provide diethyl 2-(((2S,3R,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-4-hydroxytetrahydrofuran-2-yl)methoxy)-2-benzylmalonate (19 mg, 13% yield for 3 steps) as a yellow gum.

Step 10:

To a solution of diethyl 2-(((2S,3R,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-4-hydroxytetrahydrofuran-2-yl)methoxy)-2-benzylmalonate (19 mg, 34.05 umol, 1 eq) in THF (0.2 mL) was added LiOH·H₂O (7.14 mg, 170.26 umol, 5 eq) in H₂O (70 uL) at 25° C. The reaction mixture was stirred for 5.5 h before it was diluted with H₂O (5 mL) and then acidified to pH 2-3 with 1N aq. HCl. The mixture was extracted with EtOAc (3×5 mL). The combined organic layer was washed with brine (15 mL), dried over anhydrous Na₂SO₄, filtered, and concentrated. The crude residue was dissolved in a mixture of H₂O (3 mL) and MeCN (2 mL) and then lyophilized to provide the title compound as a white solid.

¹H NMR (400 MHz, CD3OD) δ ppm 8.30 (s, 1H) 7.27 (br d, J=5.27 Hz, 2H) 7.17-7.24 (m, 1H) 7.15 (br d, J=6.78 Hz, 2H) 5.87-5.96 (m, 1H) 4.94 (br s, 1H) 4.68 (br s, 1H) 3.96-4.11 (m, 2H) 3.34-3.40 (m, 2H) 2.57 (d, J=2.51 Hz, 1H) 2.32 (s, 1H); LC/MS [M+H]=502.0.

Example 3 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3,4-dihydroxy-3-(prop-1-yn-1-yl)tetrahydrofuran-2-yl)methoxy)-2-benzylmalonic acid

Step 1:

To a solution of (3aR,5R,6aS)-5-(((tert-butyldiphenylsilyl)oxy)methyl)-2,2-dimethyldihydrofuro[2,3-d][1,3]dioxol-6 (3aH)-one (10 g, 23.44 mmol, 1 eq) in THF (100 mL) at 20° C. under N₂ atmosphere was added (prop-1-ynyl)magnesium bromide (0.5 M, 93.77 mL, 2 eq). The mixture was stirred at 40° C. for 2 h before it was diluted with saturated aq. NH₄Cl solution (250 mL). The aqueous phase was extracted with EtOAc (3×200 mL). The combined organic layer was washed with brine (200 mL), dried over Na₂SO₄, filtered and concentrated to give crude (3aR,5R,6R,6aR)-5-(((tert-butyldiphenylsilyl)oxy)methyl)-2,2-dimethyl-6-(prop-1-yn-1-yl)tetrahydrofuro[2,3-d][1,3]dioxol-6-ol (11.81 g) as a yellow gum.

Step 2:

To a solution of crude (3aR,5R,6R,6aR)-5-(((tert-butyldiphenylsilyl)oxy)-methyl)-2,2-dimethyl-6-(prop-1-yn-1-yl)tetrahydrofuro[2,3-d][1,3]dioxol-6-ol (12.2 g, 26.14 mmol, 1 eq) in pyridine (120 mL) at 20° C. was added 4-DMAP (3.51 g, 28.76 mmol, 1.1 eq) and Ac₂O (4.90 mL, 52.29 mmol, 2 eq). The mixture was stirred at 20° C. for 16 h before it was diluted with H₂O (200 mL) and extracted with EtOAc (3×100 mL). The combined organic layer was washed with brine (250 mL), dried over Na₂SO₄ and filtered. The filtrate was concentrated to give crude (3aR,5R,6R,6aR)-5-(((tert-butyldiphenylsilyl)oxy)methyl)-2,2-dimethyl-6-(prop-1-yn-1-yl)tetrahydrofuro[2,3-d][1,3]dioxol-6-yl acetate (15 g) as a yellow gum.

Step 3:

To a solution of crude (3aR,5R,6R,6aR)-5-(((tert-butyldiphenylsilyl)oxy)-methyl)-2,2-dimethyl-6-(prop-1-yn-1-yl)tetrahydrofuro[2,3-d][1,3]dioxol-6-yl acetate (15 g, 29.49 mmol, 1 eq) in THF (300 mL) at 0° C. under N₂ atmosphere was added a mixture of TBAF (1 M, 44.23 mL, 1.5 eq) and AcOH (1.26 mL, 22.12 mmol, 0.75 eq). The mixture was stirred at 20° C. for 7 h before it was diluted with saturated aq. NH₄Cl solution (300 mL) and extracted with EtOAc (3×200 mL). The combined organic layer was washed with brine (300 mL), dried over Na₂SO₄, filtered and concentrated. The crude product was purified by flash silica gel column chromatography (petroleum ether:EtOAc=1:0-1:1) to provide (3aR,5R,6R,6aR)-5-(hydroxymethyl)-2,2-dimethyl-6-(prop-1-yn-1-yl)tetrahydrofuro[2,3-d][1,3]dioxol-6-yl acetate (5.78 g, 72.5% yield) as a white solid.

Step 4:

To a solution of (3aR,5R,6R,6aR)-5-(hydroxymethyl)-2,2-dimethyl-6-(prop-1-yn-1-yl)tetrahydrofuro[2,3-d][1,3]dioxol-6-yl acetate (5.78 g, 21.39 mmol, 1 eq) in dichloroethane (60 mL) at 15° C. under N₂ atmosphere was added Rh₂(OAc)₄ (945.21 mg, 2.14 mmol, 0.1 eq) and diethyl diazomalonate (7.96 g, 42.77 mmol, 2 eq). The mixture was stirred at 40° C. for 7 h before it was concentrated to dryness. The crude product was purified by flash silica gel column chromatography (0-25% EtOAc in petroleum ether) to provide diethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-2,2-dimethyl-6-(prop-1-yn-1-yl)tetrahydrofuro[2,3-d][1,3]-dioxol-5-yl)methoxy)malonate as a yellow gum.

Step 5:

To a solution of diethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-2,2-dimethyl-6-(prop-1-yn-1-yl)tetrahydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)malonate (7.28 g, 16.99 mmol, 1 eq) in DMF (70 mL) at 20° C. was added Cs₂CO₃ (11.07 g, 33.98 mmol, 2 eq) and BnBr (3.03 mL, 25.49 mmol, 1.5 eq). The mixture was stirred at 20° C. for 2 h before it was diluted with H₂O (300 mL) and extracted with EtOAc (3×100 mL). The combined organic layer was washed with brine (200 mL), dried over Na₂SO₄, filtered and concentrated. The crude product was purified by flash silica gel gel column chromatography (petroleum ether:EtOAc=1:0-3:1) to provide diethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-2,2-dimethyl-6-(prop-1-yn-1-yl)tetrahydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)-2-benzylmalonate (7.67 g, 87% yield) as a yellow gum.

Step 6:

To a solution of diethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-2,2-dimethyl-6-(prop-1-yn-1-yl)tetrahydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)-2-benzylmalonate (7.67 g, 14.79 mmol, 1 eq) in TFA (80 mL) at 20° C. was added H₂O (6.97 mL, 387.05 mmol, 26 eq). The mixture was stirred at 20° C. for 8 h before it was quenched with saturated aq. NaHCO₃ solution to pH 7 and partitioned with EtOAc (3×100 mL). The combined organic layer was washed with brine (200 mL), dried over Na₂SO₄ and filtered. The filtrate was concentrated to dryness to provide crude diethyl 2-benzyl-2-(((2R,3S,4R)-3,4,5-trihydroxy-3-(prop-1-yn-1-yl)tetra-hydrofuran-2-yl)methoxy)malonate (5.95 g) as a yellow gum.

Step 7:

To a solution of crude diethyl 2-benzyl-2-(((2R,3S,4R)-3,4,5-trihydroxy-3-(prop-1-yn-1-yl)tetrahydrofuran-2-yl)methoxy)malonate (5.95 g, 13.63 mmol, 1 eq) in pyridine (60 mL) at 20° C. was added 4-DMAP (5.00 g, 40.90 mmol, 3 eq) and Ac₂O (6.38 mL, 68.16 mmol, 5 eq). The mixture was stirred at 20° C. for 16 h before it was diluted with H₂O (300 mL) and extracted with EtOAc (3×150 mL). The combined organic layer was washed with brine (300 mL), dried over Na₂SO₄, filtered and concentrated. The crude product was purified by flash silica gel column chromatography (petroleum ether:EtOAc=1:0-3:1) to provide diethyl 2-benzyl-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-(prop-1-yn-1-yl)tetrahydrofuran-2-yl)methoxy)malonate (5.76 g, 66% yield) as a yellow gum.

Step 8:

To a solution of diethyl 2-benzyl-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-(prop-1-yn-1-yl)tetrahydrofuran-2-yl)methoxy)malonate (1 g, 1.78 mmol, 1 eq) in MeCN (10 mL) at 20° C. was added N,O-bis(trimethylsilyl)acetamide (BSA) (1.32 mL, 5.33 mmol, 3 eq) and 2-chloroadenine (301.43 mg, 1.78 mmol, 1 eq). The mixture was stirred at 65° C. for 30 min before it was cooled to 0° C. and followed by addition of TMSOTf (642 uL, 3.56 mmol, 2 eq) dropwise. The mixture was stirred at 0° C. for 10 min and then at 65° C. for 2 h before it was quenched with saturated aq. NaHCO₃ (100 mL) and extracted with EtOAc (2×60 mL). The combined organic layer was washed with brine (100 mL) and dried over Na₂SO₄, filtered and concentrated. The crude product was purified by flash silica gel column chromatography (0-33% EtOAc in petroleum ether) to provide diethyl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-amino-2-chloro-9H-purin-9-yl)-3-(prop-1-yn-1-yl)tetrahydrofuran-2-yl)methoxy)malonate (218 mg, 18% yield) as a yellow foam.

Step 9:

To a solution of diethyl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-amino-2-chloro-9H-purin-9-yl)-3-(prop-1-yn-1-yl)tetrahydrofuran-2-yl)methoxy)malonate (218 mg, 324.37 umol, 1 eq) in THF (2 mL) was added LiOH·H₂O (136.12 mg, 3.24 mmol, 10 eq) in H₂O (2 mL) at 20° C. The mixture was heated at 45° C. for 2 h before it was diluted with H₂O (10 mL) and extracted with EtOAc (10 mL). The organic layer was discarded and the aqueous phase was acidified with 2 N aq. HCl to pH 2-3. Then the aqueous phase was extracted with EtOAc (3×20 mL). The combined organic layer was washed with brine (30 mL), dried over Na₂SO₄, filtered and concentrated. The crude product was purified by preparative HPLC to provide the title compound (39.8 mg, 23% yield) as a white solid.

¹H NMR (DMSO-d₆, 400 MHz) δ ppm 12.70-14.12 (m, 2H), 8.37 (s, 1H), 7.80 (br s, 2H), 7.19 (br d, J=7.03 Hz, 2H), 7.00-7.11 (m, 3H), 5.88-6.03 (m, 2H), 5.81 (d, J=7.53 Hz, 1H), 4.78 (br s, 1H), 4.12 (dd, J=4.52, 3.01 Hz, 1H), 3.95 (br dd, J=9.91, 4.89 Hz, 1H), 3.82 (br d, J=8.53 Hz, 1H), 3.25 (s, 2H), 1.81 (s, 3H); LC/MS [M+H]=532.0.

Example 4 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-(cyclopropylethynyl)-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-benzylmalonic acid

Step 1:

To a solution of ethynylcyclopropane (4.96 g, 75.02 mmol, 6.22 mL, 2 eq) in THF (80 mL) at −78° C. under N₂ atmosphere was added n-BuLi (2.5 M, 30.01 mL, 2 eq) dropwise. The solution was stirred at −78° C. for 0.5 h and followed by addition of a solution of (3aR,5R,6aS)-5-(((tert-butyldiphenylsilyl)oxy)methyl)-2,2-dimethyldihydrofuro[2,3-d][1,3]-dioxol-6 (3aH)-one (16.0 g, 37.51 mmol, 1 eq) in THF (60 mL) dropwise. Then the solution was allowed to warm to 20° C. and stirred for 1 h before it was then cooled to 0° C. and quenched with water (120 mL). The mixture was extracted with EtOAc (2×120 mL). The combined organic layer was washed with brine (200 mL), and dried by Na₂SO₄, filtered and concentrated. The crude was purified by Combi-flash on silica gel (0-15% ethyl acetate in petroleum ether) to give (3aR,5R,6R,6aR)-5-(((tert-butyldiphenylsilyl)oxy)-methyl)-6-(cyclopropylethynyl)-2,2-dimethyltetrahydrofuro[2,3-d][1,3]dioxol-6-ol (15.8 g, 86% yield) as a syrup.

Step 2:

To a solution of (3aR,5R,6R,6aR)-5-(((tert-butyldiphenylsilyl)oxy)methyl)-6-(cyclo-propylethynyl)-2,2-dimethyltetrahydrofuro[2,3-d][1,3]dioxol-6-ol (15.8 g, 32.07 mmol, 1 eq) in pyridine (160 mL) at 20° C. was added 4-DMAP (4.70 g, 38.48 mmol, 1.2 eq) and Ac₂O (9.01 mL, 96.21 mmol, 3 eq). The solution was stirred for 3 h before it was diluted with water (200 mL) and extracted with ethyl acetate (2×200 mL). The combined organic layer was washed with brine (400 mL), dried by Na₂SO₄, filtered and concentrated. The crude residue was purified by Combi-flash on silica gel (0-15% ethyl acetate in petroleum ether) to give (3aR,5R,6R,6aR)-5-(((tert-butyldiphenylsilyl)oxy)methyl)-6-(cyclopropylethynyl)-2,2-dimethyltetrahydrofuro[2,3-d][1,3]dioxol-6-yl acetate (14.7 g, 86% yield) as a clear syrup.

Step 3:

To a solution of (3aR,5R,6R,6aR)-5-(((tert-butyldiphenylsilyl)oxy)methyl)-6-(cyclopropylethynyl)-2,2-dimethyltetrahydrofuro[2,3-d][1,3]dioxol-6-yl acetate (14.7 g, 27.49 mmol, 1 eq) in THF (150 mL) at 0° C. was added a solution of TBAF (1 M, 41.24 mL, 1.5 eq) and AcOH (1.18 mL, 20.62 mmol, 0.75 eq). The solution was stirred at 20° C. for 16 h before it was diluted with water (300 mL) and extracted with ethyl acetate (2×200 mL). The combined organic layer was washed with water (400 mL), brine (400 mL), dried by Na₂SO₄, filtered and concentrated. The crude was purified by Combi-flash on silica gel (20-60% ethyl acetate in petroleum ether) to give (3aR,5R,6R,6aR)-6-(cyclopropylethynyl)-5-(hydroxymethyl)-2,2-dimethyltetrahydrofuro[2,3-d][1,3]dioxol-6-yl acetate (8.15 g, 100% yield) as a white solid.

Step 4:

To a solution of (3aR,5R,6R,6aR)-6-(cyclopropylethynyl)-5-(hydroxymethyl)-2,2-dimethyltetrahydrofuro[2,3-d][1,3]dioxol-6-yl acetate (8.15 g, 27.50 mmol, 1 eq) in dichloroethane (80 mL) at 20° C. under N₂ atmosphere was added Rh₂(OAc)₄ (1.00 g, 2.26 mmol, 0.08 eq) and a solution of diethyl diazomalonate (10.24 g, 55.01 mmol, 2 eq) in dichloroethane (20 mL). The green solution was stirred for 16 h before it was concentrated. The crude was purified by Combi-flash on silica gel (15-50% ethyl acetate in petroleum ether) to give diethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-6-(cyclopropylethynyl)-2,2-dimethyl-tetrahydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)malonate (9.52 g, 76% yield) as a yellow oil.

Step 5:

To a solution of diethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-6-(cyclopropylethynyl)-2,2-dimethyltetrahydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)malonate (4.50 g, 9.90 mmol, 1 eq) in DMF (50 mL) at 20° C. was added Cs₂CO₃ (9.68 g, 29.71 mmol, 3 eq) and benzyl bromide (1.76 mL, 14.85 mmol, 1.5 eq). The suspension was stirred for 16 h before it was diluted with water (80 mL) and extracted with ethyl acetate (3×80 mL). The combined organic layer was washed with water (200 mL), brine (200 mL), dried by Na₂SO₄, filtered and concentrated. The crude was purified by Combi-flash on silica gel (15-50% ethyl acetate in petroleum ether) to give diethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-6-(cyclo-propylethynyl)-2,2-dimethyltetrahydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)-2-benzyl-malonate (4.10 g, 76% yield) as a colorless syrup.

Step 6:

To a solution of diethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-6-(cyclopropylethynyl)-2,2-dimethyltetrahydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)-2-benzylmalonate (4.10 g, 7.53 mmol, 1 eq) in DCM (50 mL) at 0° C. was added H₂O (10 mL) and TFA (50 mL). The solution was stirred at 20° C. for 2 h before it was quenched with saturated aq. NaHCO₃ (80 mL) to pH˜7. The reaction mixture was exacted with DCM (100 mL). The organic layer was washed with brine (10 mL), dried by Na₂SO₄, filtered and concentrated to give crude diethyl 2-(((2R,3S,4R)-3-acetoxy-3-(cyclopropylethynyl)-4,5-dihydroxytetrahydrofuran-2-yl)methoxy)-2-benzylmalonate (3.80 g) as a yellow gum.

Step 7:

To a solution of crude diethyl diethyl 2-(((2R,3S,4R)-3-acetoxy-3-(cyclopropyl-ethynyl)-4,5-dihydroxytetrahydrofuran-2-yl)methoxy)-2-benzylmalonate (3.80 g, 7.53 mmol, 1 eq) in pyridine (40 mL) at 20° C. was added 4-DMAP (2.76 g, 22.60 mmol, 3 eq) and Ac₂O (5.64 mL, 60.25 mmol, 8 eq). The solution was stirred for 16 h before it was diluted with water (80 mL) and extracted with ethyl acetate (2×80 mL). The combined organic layer was washed with water (150 mL), brine (150 mL), dried by Na₂SO₄, filtered and concentrated. The crude was purified by Combi-flash on silica gel (10-50% ethyl acetate in petroleum ether) to give diethyl 2-benzyl-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-(cyclopropylethynyl)-tetrahydro-furan-2-yl)methoxy)malonate (2.91 g, 66% yield) as a yellow gum.

Step 8:

To a solution of diethyl 2-benzyl-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-(cyclopropylethynyl)tetrahydrofuran-2-yl)methoxy)malonate (980 mg, 1.66 mmol, 1 eq) in MeCN (24 mL) at 25° C. was added 2-chloroadenine (338.80 mg, 2.00 mmol, 1.2 eq) and BSA (987.71 uL, 4.00 mmol, 2.4 eq). The suspension was stirred at 65° C. for 0.5 h as it turned clear. The resulting solution was cooled down to 0° C. and followed by addition of TMSOTf (444.06 mg, 2.00 mmol, 361.03 uL, 1.2 eq) dropwise. The reaction mixture was stirred at 40° C. for 4 h before it was allowed to cool to room temperature. The reaction mixture was diluted with water (20 mL) and extracted with ethyl acetate (3×20 mL). The combined organic layer was washed with brine (50 mL), dried by Na₂SO₄, filtered and concentrated. The crude was purified by Combi-flash on silica gel (30-80% ethyl acetate in petroleum ether) to give diethyl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-amino-2-chloro-9H-purin-9-yl)-3-(cyclopropylethynyl)tetrahydrofuran-2-yl)methoxy)malonate (270 mg, 23% yield) as a yellow gum.

Step 9:

To a solution of diethyl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-amino-2-chloro-9H-purin-9-yl)-3-(cyclopropylethynyl)tetrahydrofuran-2-yl)-methoxy)malonate (270 mg, 386.75 umol, 1 eq) in THF (8 mL) was added aq. LiOH solution (1 M, 5.80 mL, 15 eq). The mixture was stirred at 20° C. for 16 h before it was treated with 1N HCl to adjust the pH to 5. The mixture was concentrated. The crude residue was purified by preparative HPLC to give the title compound (23 mg, 11% yield) as a white solid.

¹H NMR (400 MHz, CD3OD) δ ppm 8.04 (s, 1H) 7.14-7.27 (m, 2H) 7.01-7.08 (m, 3H) 5.92 (d, J=6.63 Hz, 1H) 4.70-4.83 (m, 1H) 4.24 (t, J=3.50 Hz, 1H) 4.02 (t, J=3.31 Hz, 2H) 3.31-3.45 (m, 2H) 1.25-1.33 (m, 1H) 0.72-0.79 (m, 2H) 0.63-0.71 (m, 2H); LC/MS [M+H]=559.0.

Example 5 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-((2-chloropyridin-4-yl)methyl)malonic acid

Proceeding as described in Example 1 above by substituting BnBr with 2-chloro-4-(chloromethyl)pyridine provided the title compound as a white solid.

¹H NMR (CD3OD, 400 MHz) δ ppm 8.40 (s, 1H), 8.00 (d, J=5.13 Hz, 1H), 7.36 (s, 1H), 7.23 (d, J=5.13 Hz, 1H), 6.01 (d, J=7.63 Hz, 1H), 5.08 (d, J=7.63 Hz, 1H), 4.39 (dd, J=4.88, 2.75 Hz, 1H), 4.16 (dd, J=10.07, 5.19 Hz, 1H), 4.05 (dd, J=10.01, 2.63 Hz, 1H), 3.47 (s, 2H), 3.05 (s, 1H); LC/MS [M+H]=553.1.

Example 6 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2,4-dioxo-3,4-dihydropyrimidin-1 (2H)-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

Step 1:

To a mixture of (3aR,5R,6R,6aR)-5-(((tert-butyldiphenylsilyl)oxy)methyl)-6-ethynyl-2,2-dimethyltetrahydrofuro[2,3-d][1,3]dioxol-6-yl acetate (27.4 g, 55.39 mmol, 1 eq) in THF (250 mL) at 0° C. was added AcOH (2.38 mL, 41.54 mmol, 0.75 eq) in TBAF (1 M, 83.09 mL, 1.5 eq). The mixture was stirred at 15° C. for 15 h before it was partitioned between water (800 mL) and EtOAc (300 mL). The aqueous phase was further extracted with EtOAc (3×200 mL). The combined organic layer was washed with brine (300 mL), dried over anhydrous Na₂SO₄, filtered and concentrated under reduced pressure to give a residue. The residue was purified by column chromatography on SiO₂ (11-33% EtOAc in petroleum ether) to give (3aR,5R,6R,6aR)-6-ethynyl-5-(hydroxymethyl)-2,2-dimethyltetrahydrofuro-[2,3-d][1,3]dioxol-6-yl acetate (15.2 g, 91% yield) as alight yellow solid.

Step 2:

To a mixture of (3aR,5R,6R,6aR)-6-ethynyl-5-(hydroxymethyl)-2,2-dimethyltetra-hydrofuro[2,3-d][1,3]dioxol-6-yl acetate (15.2 g, 59.32 mmol, 1 eq) in dichloroethane (150 mL) at 0° C. was added Rh₂(OAc)₄ (1.31 g, 2.97 mmol, 0.05 eq) and diethyl diazomalonate (13.25 g, 71.18 mmol, 1.2 eq) in dichloroethane (30 mL). The mixture was stirred at 15° C. under N₂ atmosphere for 15 h before additional amount of diethyl diazomalonate (6 g) in dichloroethane (15 mL) was added. The mixture was stirred further at 15° C. for 2 h before it was concentrated under reduced pressure. The residue was purified by column chromatography on silica gel (11-33% EtOAc in petroleum ether) to give diethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-6-ethynyl-2,2-dimethyltetra-hydrofuro-[2,3-d][1,3]dioxol-5-yl)methoxy)malonate (15 g, 61% yield) as a white solid.

Step 3:

To a mixture of diethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-6-ethynyl-2,2-dimethyltetra-hydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)malonate (14 g, 33.78 mmol, 1 eq) in DMF (140 mL) at 25° C. was added Cs₂CO₃ (22.01 g, 67.57 mmol, 2 eq) and BnBr (6.02 mL, 50.68 mmol, 1.5 eq). The mixture was stirred at 25° C. for 3 h before it was filtered and the filter cake was washed with EtOAc (50 mL). The filtrate was diluted with water (400 mL) and extracted with EtOAc (3×150 mL). The combined organic layer was washed with brine (200 mL), dried over anhydrous Na₂SO₄, filtered and concentrated under reduced pressure. The residue was purified by flash silica gel column chromatography (0-33% EtOAc in petroleum ether) to give diethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-6-ethynyl-2,2-dimethyltetra-hydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)-2-benzylmalonate (13.3 g, 78% yield) as a colorless oil.

Step 4:

To a mixture of diethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-6-ethynyl-2,2-dimethyltetra-hydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)-2-benzylmalonate (13.20 g, 26.16 mmol, 1 eq) in DCM (100 mL) and H₂O (20 mL, 1.11 mol, 42 eq) was added TFA (100 mL, 1.35 mol, 52 eq). The mixture was stirred at 15° C. for 12 h before water (200 mL) was added. The aqueous phase was extracted with DCM (2×100 mL). The combined organic extract was washed with saturated aq. NaHCO₃ (2×100 mL), brine (100 mL), dried over anhydrous Na₂SO₄, filtered and concentrated under reduced pressure. The residue was purified by flash column chromatography (SiO₂, petroleum ether:Ethyl acetate=10:1 to 1:3) to give diethyl 2-benzyl-2-(((2R,3S,4R)-3-ethynyl-3,4,5-trihydroxytetrahydrofuran-2-yl)methoxy)malonate (7.8 g, 71% yield) as a colorless oil.

Step 5:

To a mixture of diethyl 2-benzyl-2-(((2R,3S,4R)-3-ethynyl-3,4,5-trihydroxytetra-hydrofuran-2-yl)methoxy)malonate (7.8 g, 18.46 mmol, 1 eq) in pyridine (70 mL) at 15° C. was added 4-DMAP (6.77 g, 55.39 mmol, 3 eq) and Ac₂O (17.29 mL, 184.65 mmol, 10 eq). The mixture was stirred for 15 h before water (400 mL) was added. The mixture was extracted with EtOAc (3×200 mL). The combined organic layer was washed with 1N aq. HCl (2×200 mL), saturated aq. NaHCO₃ (300 mL), brine (300 mL), dried over anhydrous Na₂SO₄, filtered and concentrated under reduced pressure. The residue was purified by flash silica gel column chromatography (petroleum ether:Ethyl acetate=1:0 to 2:1) to give the desired product (7 g). This product was triturated with EtOH (10 mL) and filtered to give diethyl 2-benzyl-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-ethynyltetrahydrofuran-2-yl)methoxy)-malonate (3.79 g, 37% yield) as a white solid. The filtrate was concentrated under reduced pressure to give slightly impure additional product (3 g).

Step 6:

To a solution of diethyl 2-benzyl-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-ethynyltetra-hydrofuran-2-yl)methoxy)malonate (116 mg, 0.21 mmol, 1.0 eq) in MeCN (3 mL) at 25° C. was added uracil (28 mg, 0.25 mmol, 1.2 eq) and followed by N,O-bis(trimethylsilyl)-acetamide (BSA) (124 uL, 0.51 mmol, 2.4 eq). The resulting suspension was heated at 65° C. for 30 min as it became clear. The reaction mixture was cooled to 0° C. and followed by dropwise addition of TMSOTf (46 uL, 0.25 mmol, 1.2 eq). The reaction mixture was allowed to warm up and heated at 65° C. for 3 h as all of the starting material was consumed. The reaction was quenched with cold saturated aq. NaHCO₃ solution (3 mL) and diluted with EtOAc (15 mL). The organic layer was separated, washed with H₂O (2×10 mL), brine, dried (MgSO₄), filtered and concentrated. The crude residue was purified by flash silica gel column chromatography (0-75% EtOAc in hexanes) to provide the product diethyl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(2,4-dioxo-3,4-dihydro-pyrimidin-1 (2H)-yl)-3-ethynyl-tetrahydrofuran-2-yl)methoxy)malonate (104 mg, 82% yield).

Step 7:

To a solution of diethyl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(2,4-dioxo-3,4-dihydropyrimidin-1 (2H)-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-malonate (100 mg, 0.166 umol, 1 eq) in a mixture of THF (1 mL) and MeOH (2 mL) was added aq. LiOH solution (1 M, 3 mL). The mixture was stirred at 40° C. for 24 h before the organic volatile was removed under reduced pressure. The residue was diluted with water (2 mL) and treated with TN HCl to adjust the pH to 4. The mixture was extracted with EtOAc (3×10 mL). The combined organic layer was washed with brine, dried (MgSO₄), filtered and concentrated to provide the title compound (67 mg) as a white solid.

¹H NMR (CD₃OD, 300 MHz) δ 8.09 (bs, 1H), 7.86 (d, J=8 Hz, 1H), 7.33-7.16 (m, 5H), 6.01 (d, J=7 Hz, 1H), 5.07 (d, J=8 Hz, 1H), 4.45 (d, J=7 Hz, 1H), 4.22 (bs, 1H), 4.11-3.94 (m, 2H), 3.55-3.31 (m, 2H), 2.95 (s, 1H), LC/MS [M+H]=461.0.

Example 7 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(pyridin-4-ylmethyl)malonic acid

Step 1:

To a mixture of diethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-6-ethynyl-2,2-dimethyltetra-hydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)malonate (1.2 g, 2.90 mmol, 1 eq) in DMF (20 mL) at 20° C. was added Cs₂CO₃ (6.60 g, 20.27 mmol, 7 eq) and 4-(chloromethyl) pyridine hydrochloride (1.90 g, 11.58 mmol, 4 eq). The mixture was stirred for 2 h before it was filtered and the filter cake was washed with EtOAc (20 mL). The filtrate was diluted with water (60 mL) and extracted with EtOAc (3×50 mL). The combined extract was washed with water (2×50 mL), saturated aq. NH₄Cl (50 mL), brine (50 mL), dried over anhydrous Na₂SO₄, filtered and concentrated under reduced pressure. The residue was purified by column chromatography on SiO₂ (14-33% EtOAc in petroleum ether) to give diethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-6-ethynyl-2,2-dimethyltetrahydrofuro[2,3-d][1,3]-dioxol-5-yl)methoxy)-2-(pyridin-4-ylmethyl)malonate (900 mg, 61% yield) as a yellow oil.

Step 2:

To a mixture of diethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-6-ethynyl-2,2-dimethyltetra-hydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)-2-(pyridin-4-ylmethyl)-malonate (900 mg, 1.78 mmol, 1 eq) in DCM (5 mL) and H₂O (1 mL, 55.51 mmol, 31.18 eq) was added TFA (5 mL, 67.53 mmol, 37.93 eq). The mixture was stirred at 20° C. for 12 h before it was concentrated under reduced pressure. The crude residue was azeotroped with DCM (3×10 mL) under reduced pressure to provide crude diethyl 2-(((2R,3S,4R)-3-ethynyl-3,4,5-trihydroxytetra-hydrofuran-2-yl)methoxy)-2-(pyridin-4-ylmethyl)malonate (1.1 g) as a brown oil.

Step 3:

To a mixture of crude diethyl 2-(((2R,3S,4R)-3-ethynyl-3,4,5-trihydroxy-tetrahydro-furan-2-yl)methoxy)-2-(pyridin-4-ylmethyl)malonate (1.1 g, 2.60 mmol, 1 eq) in pyridine (8 mL) at 20° C. was added 4-DMAP (952.17 mg, 7.79 mmol, 3 eq) and Ac₂O (2.43 mL, 25.98 mmol, 10 eq). The mixture was stirred for 12 h before it was partitioned between water (30 mL) and EtOAc (20 mL). The aqueous phase was further extracted with EtOAc (2×20 mL). The combined extract was washed with water (20 mL), 0.5 N aq. HCl (2×10 mL), and brine (20 mL), dried over anhydrous Na₂SO₄, filtered and concentrated under reduced pressure. The residue was purified by flash column chromatography on SiO₂ (25-50% EtOAc in petroleum ether) to give diethyl 2-(pyridin-4-ylmethyl)-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-ethynyl-tetrahydrofuran-2-yl)methoxy)malonate (640 mg, 45% yield) as a brown syrup.

Step 4:

To a mixture of diethyl 2-(pyridin-4-ylmethyl)-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (40 mg, 72.79 umol, 1 eq) and 2-chloroadenine (13.58 mg, 80.07 umol, 1.1 eq) in MeCN (1.5 mL) was added BSA (44.98 uL, 181.98 umol, 2.5 eq) at 25° C. under N₂ atmosphere. The mixture was stirred at 65° C. for 0.5 h before it was cooled to 0° C. and followed by dropwise addition of TMSOTf (26.31 uL, 145.58 umol, 2 eq). The mixture was stirred at 0° C. for 0.5 h and then at 65° C. for 2 h. The reaction mixture was cooled to room temperature and quenched with saturated aq. NaHCO₃ (6 mL). The mixture was extracted with EtOAc (3×8 mL). The combined organic layer was washed with brine (5 mL), dried over anhydrous Na₂SO₄, filtered and concentrated under reduced pressure. The residue was purified by preparative TLC (EtOAc) to provide diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-2-(pyridin-4-ylmethyl)-malonate (13 mg, 26% yield) was obtained as a yellow gum.

Step 5:

To a mixture of diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-2-(pyridin-4-ylmethyl)-malonate (50 mg, 75.87 umol, 1 eq) in THF (1 mL) was added 1N aq. LiOH (1 mL). The mixture was stirred at 50° C. for 1 h before it was cooled to room temperature and adjusted the pH 6-7 with 2N aq. HCl solution. The mixture was concentrated under reduced pressure and the residue was purified by preparative reverse-phase HPLC to provide the title compound (34 mg) as a white solid.

¹H NMR (CD₃OD, 300 MHz) δ 8.50 (bs, 1H), 8.32 (d, J=4 Hz, 2H), 7.50 (d, J=5 Hz, 2H), 6.01 (d, J=7 Hz, 1H), 4.80 (d, J=6 Hz, 1H), 4.38 (q, J=3 Hz, 1H), 4.10-3.95 (m, 2H), 3.45 (bs, 2H), 3.06 (s, 1H); LC/MS [M+H]=519.0.

Example 8 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(furan-3-ylmethyl)malonic acid

Step 1:

To a mixture of PPh₃ (4.28 g, 16.31 mmol, 1.6 eq) and CBr₄ (4.06 g, 12.23 mmol, 1.2 eq) in DCM (20 mL) at 0° C. under N₂ atmosphere was added furan-3-ylmethanol (1 g, 10.19 mmol, 1 eq) in DCM (5 mL) dropwise. The mixture was stirred at 20° C. for 2 h before it was quenched with saturated aq. NaHCO₃ (30 mL) and then extracted with EtOAc (2×15 mL).

The combined organic layer was washed with brine (30 mL), dried over anhydrous Na₂SO₄, filtered and concentrated under reduced pressure to provide crude 3-(bromomethyl)furan (2.9 g) as yellow gum which was used in the next step directly without further purification.

Step 2:

To a solution of diethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-6-ethynyl-2,2-dimethyltetra-hydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)malonate (1 g, 2.41 mmol, 1 eq) in DMF (5 mL) at 20° C. was added Cs₂CO₃ (2.36 g, 7.24 mmol, 3 eq) and crude 3-(bromomethyl)furan (2.9 g) in DMF (6 mL). The mixture was stirred for 2 h before it was partitioned between water (30 mL) and EtOAc (30 mL). The aqueous phase was extracted with EtOAc (3×15 mL).

The combined organic extract was washed with water (20 mL), saturated aq. NH₄Cl (2×20 mL), brine (20 mL), dried over anhydrous Na₂SO₄, filtered and concentrated under reduced pressure. The residue was purified by column chromatography on SiO₂ (10-25% EtOAc in petroleum ether) to give diethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-6-ethynyl-2,2-dimethyltetra-hydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)-2-(furan-3-ylmethyl)malonate (375 mg, 31% yield) as a light yellow oil.

Step 3:

To a mixture of diethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-6-ethynyl-2,2-dimethyltetra-hydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)-2-(furan-3-ylmethyl)-malonate (375 mg, 758.36 umol, 1 eq) in DCM (2 mL) and H₂O (0.4 mL, 22.20 mmol, 29 eq) was added TFA (2 mL, 27.01 mmol, 36 eq). The mixture was stirred at 20° C. for 12 h before it was concentrated under reduced pressure to provide crude diethyl 2-(((2R,3S,4R)-3-ethynyl-3,4,5-trihydroxy-tetrahydrofuran-2-yl)methoxy)-2-(furan-3-ylmethyl)malonate (420 mg) as an oil which was used in next step without further purification.

Step 4:

To a mixture of crude diethyl 2-(((2R,3S,4R)-3-ethynyl-3,4,5-trihydroxytetrahydro-furan-2-yl)methoxy)-2-(furan-3-ylmethyl)malonate (420 mg, 1.02 mmol, 1 eq) in pyridine (4 mL) at 20° C. was added Ac₂O (954 uL, 10.18 mmol, 10 eq) and 4-DMAP (373 mg, 3.06 mmol, 3 eq). The mixture was stirred for 12 h before it was partitioned between water (15 mL) and EtOAc (10 mL). The aqueous phase was extracted with EtOAc (2×20 mL). The combined organic extract was washed with water (10 mL), 0.5N aq. HCl (2×5 mL), brine (10 mL), dried over anhydrous Na₂SO₄, filtered and concentrated. The residue was purified by preparative TLC (petroleum ether:EtOAc=3:1) to give diethyl 2-(furan-3-ylmethyl)-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (95 mg, 17% yield) as a yellow oil.

Step 5:

To a mixture of diethyl 2-(furan-3-ylmethyl)-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (50 mg, 92.85 umol, 1 eq) and 2-chloro-addenine (17.32 mg, 102.14 umol, 1.1 eq) in MeCN (1.2 mL) was added BSA (57.38 uL, 232.13 umol, 2.5 eq) at 25° C. under N₂ atmosphere. The mixture was stirred at 65° C. for 0.5 h before it was cooled to 0° C. and followed by dropwise addition of TMSOTf (33.56 uL, 185.70 umol, 2 eq). The mixture was stirred at 0° C. for 0.5 h and then at 65° C. for 2 h before it was cooled to room temperature and quenched with saturated aq. NaHCO₃ solution (2 mL). The mixture was extracted with EtOAc (3×2 mL). The combined organic layer was washed with brine (2 mL), dried over anhydrous Na₂SO₄, filtered and concentrated under reduced pressure. The residue was purified by preparative TLC (petroleum ether:EtOAc=1:1) to provide diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-2-(furan-3-ylmethyl)malonate (17 mg, 29% yield) as a yellow gum.

Step 6:

To a mixture of diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-2-(furan-3-ylmethyl)-malonate (33 mg, 50.92 umol, 1 eq) in THF (1 mL) was added 1N aq. LiOH (1 mL). The mixture was stirred at 20° C. for 3 h before it was extracted with EtOAc (2 mL). The organic layer was discarded. The aqueous phase was adjusted the pH 2-3 with 2N aq. HCl before it was extracted with EtOAc (4×5 mL). The combined organic extract was washed with brine (3 mL), dried over anhydrous Na₂SO₄, filtered and concentrated under reduced pressure. The residue was dissolved in a mixture of MeCN (1 mL) and H₂O (1 mL) and then dried by lyophilization to provide the title compound (10.0 mg, 37% yield) as a white solid.

¹H NMR (400 MHz, DMSO-d₆) δ ppm 8.48 (s, 1H) 7.81 (br s, 2H) 7.35 (s, 2H) 6.29 (s, 1H) 6.22 (br s, 1H) 6.02 (br d, J=6.50 Hz, 1H) 5.83 (d, J=7.50 Hz, 1H) 4.75-4.90 (m, 1H) 4.16 (dd, J=4.75, 2.75 Hz, 1H) 3.92 (br dd, J=10.07, 5.07 Hz, 1H) 3.77 (br d, J=8.00 Hz, 1H) 3.48 (s, 1H) 3.08 (s, 2H); LC/MS [M+H]=507.9.

Example 9 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)malonic acid

Step 1:

To a solution of diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-N,N′-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy-)malonate (7.26 g, 4.92 mmol, 1 eq) in DMF (80 mL) at 25° C. was added K₂CO₃ (13.60 g, 98.40 mmol, 20 eq). The reaction mixture was stirred for 0.5 h and followed by addition of 1-(bromomethyl)-4-nitro-benzene (15.94 g, 73.80 mmol, 15 eq). The reaction mixture was stirred for 24 h before it was diluted with H₂O (300 mL) and extracted with EtOAc (3×60 mL). The combined organic layer was washed with brine (100 mL), dried over Na₂SO₄, filtered and concentrated. The crude residue was purified by flash silica gel column chromatography (petroleum ether:EtOAc=10:1-2:1) to provide diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-((tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyltetra-hydrofuran-2-yl)methoxy)-2-(4-nitrobenzyl)malonate (2.36 g) was obtained as a brown gum.

Step 2:

To a solution of diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-((tert-butoxycarbonyl)-amino)-2-chloro-9H-purin-9-yl)-3-ethynyltetra-hydrofuran-2-yl)methoxy)-2-(4-nitrobenzyl)-malonate (2.26 g, 2.81 mmol, 1 eq) in EtOH (23 mL) at 0° C. was added Fe (786 mg, 14.07 mmol, 5 eq) and NH₄Cl (151 mg, 2.81 mmol, 1 eq) in H₂O (8.5 mL). The reaction mixture was stirred at 50° C. for 4 h before it was filtered and the filtrate was concentrated. The crude residue was purified by flash silica gel column chromatography (petroleum ether:EtOAc=1:0-1:1) to provide diethyl 2-(4-aminobenzyl)-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-((tert-butoxycarbonyl)-amino)-2-chloro-9H-purin-9-yl)-3-ethynyltetra-hydrofuran-2-yl)methoxy)-malonate (280 mg) as a yellow foam.

Step 3:

To a solution of diethyl 2-(4-aminobenzyl)-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-((tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)-methoxy)malonate (280 mg, 362.14 umol, 1 eq) in DCM (3 mL) at 0° C. was added 1-chloro-3-isocyanatopropane (86.59 mg, 724.28 umol, 2 eq). The reaction mixture was stirred at 25° C. for 16 h before it was concentrated. The crude residue was purified by preparative TLC (petroleum ether:EtOAc=1:0-1:1) to provide diethyl 2-(4-(3-(3-chloropropyl)ureido)-benzyl)-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-((tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (120 mg, 33% yield) as a foam.

Step 4:

To a solution of diethyl 2-(4-(3-(3-chloropropyl)ureido)benzyl)-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-((tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyltetra-hydrofuran-2-yl)methoxy)malonate (120 mg, 134.42 umol, 1 eq) in THF (1.2 mL) at 0° C. was added NaH (11 mg, 268.84 umol, 60% in mineral oil, 2 eq). The reaction mixture was stirred at 25° C. for 2 h before it was quenched with H₂O (0.2 mL) at 0° C. The reaction mixture was then stirred at 25° C. for 16 h. The reaction mixture was acidified to pH 3-4 with 1N aq. HCl solution and then extracted with EtOAc (3×5 mL). The combined organic layer was washed with brine (15 mL), dried over anhydrous Na₂SO₄, filtered and concentrated to provide crude 2-(((2R,3S,4R,5R)-5-(6-((tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxo-tetrahydropyrimidin-1 (2H)-yl)benzyl)malonic acid (77 mg, 73% yield) as a white solid.

Step 5:

To a solution of crude 2-(((2R,3S,4R,5R)-5-(6-((tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxotetra-hydropyrimidin-1 (2H)-yl)benzyl)malonic acid (76 mg, 106.13 umol, 1 eq) in DCM (0.5 mL)) at 0° C. was added TFA (0.25 mL, 3.38 mmol, 32 eq). The reaction mixture was stirred at 25° C. for 2 h before it was concentrated. The residue was re-dissolved with saturated aq. NaHCO₃ solution (5 mL) and extracted EtOAc (3×5 mL). The combined organic layer was washed with brine (15 mL), dried over anhydrous Na₂SO₄, filtered and concentrated. The crude residue was purified by preparative reversed-phase HPLC to provide the title compound (8.6 mg, 12% yield) as a white solid.

¹H NMR (CD₃OD, 300 MHz) δ 8.28 (s, 1H), 7.11 (d, J=8.52 Hz, 2H), 7.02 (d, J=8.52 Hz, 2H), 5.99 (d, J=7.44 Hz, 1H), 4.79 (d, J=7.41 Hz, 1H), 4.29 (t, J=2.76 Hz, 1H), 4.01-3.91 (m, 2H), 3.54-3.41 (m, 4H), 3.36-3.32 (m, 2H), 3.05 (s, 1H), 2.03-1.94 (m, 2H); LC/MS [M+H]=616.2.

Example 10 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxopiperidin-1-yl)benzyl)malonic acid

Step 1:

To a solution of crude diethyl 2-(4-aminobenzyl)-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-((tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)-methoxy)malonate (140 mg, 160 umol, 1 eq) in DCM (2 mL) at 25° C. was added TEA (107 mg, 1.06 mmol, 147 uL, 6.59 eq) and followed by 5-chloropentanoyl chloride (24.9 uL, 192 umol, 1.2 eq). The mixture was stirred for 1 h before it was partitioned between DCM (20 mL) and H₂O (20 mL). The organic phase was washed with H₂O (10 mL), dried over Na₂SO₄, filtered and concentrated under reduced pressure. The residue was purified by preparative TLC (petroleum ether:EtOAc=1:1) to give diethyl 2-(4-(5-chloropentanamido)-benzyl)-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-((tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (130 mg, 69% yield) as a yellow gum.

Step 2:

To a solution of diethyl 2-(4-(5-chloropentanamido)-benzyl)-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-((tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydro-furan-2-yl)methoxy)malonate (104 mg, 105 umol, 1 eq) in THF (2 mL) at 25° C. was added NaH (25.2 mg, 630 umol, 60% in mineral oil, 6 eq). The mixture was stirred for 4 h before it was quenched with H₂O (1 mL). The reaction mixture was stirred at 20° C. for 14 before it was partitioned between EtOAc (10 mL) and water (20 mL). The aqueous phase was acidified to pH 5-6 with 2N aq. HCl solution before it was partitioned between EtOAc (20 mL) and brine (10 mL), dried over anhydrous Na₂SO₄, filtered and concentrated under reduced pressure to give crude 2-(((2R,3S,4R,5R)-5-(6-((tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxopiperidin-1-yl)benzyl)malonic acid (58 mg) as a colorless gum.

Step 3:

To a mixture of crude 2-(((2R,3S,4R,5R)-5-(6-((tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxopiperidin-1-yl)benzyl)malonic acid (58 mg, 81 umol, 1 eq) in DCM (500 uL) was added TFA (400 uL, 5.40 mmol, 67 eq). The mixture was stirred at 20° C. for 2 h before it was quenched with 2N aq. LiOH (500 uL). The mixture was partitioned between EtOAc (10 mL) and water (10 mL). The aqueous phase was adjusted to pH 5-6 with 2M aq. HCl solution. The aqueous phase was partitioned between EtOAc (2×20 mL) and brine (5 mL), dried over anhydrous Na₂SO₄, filtered and concentrated under reduced pressure. The crude product was purified by preparative HPLC and lyophilized to give the title compound (6.9 mg, 14% yield) as a white solid.

¹H NMR (400 MHz, DMSO-d₆) δ ppm 8.32 (s, 1H) 7.33 (d, J=8.53 Hz, 2H) 6.98 (d, J=8.28 Hz, 2H) 5.98 (d, J=7.53 Hz, 1H) 4.79 (m, 1H) 4.28 (t, J=2.76 Hz, 1H) 4.04 (br s, 2H) 3.39-3.54 (m, 4H) 3.05 (s, 1H) 2.43 (m, 2H) 1.88 (br t, J=2.89 Hz, 4H); LC/MS [M+H]=615.3.

Example 11 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(1-(methoxymethyl)-2-oxo-1,2-dihydropyridin-3-yl)benzyl)malonic acid

Step 1:

To a solution of 3-bromopyridin-2 (1H)-one (2.25 g, 12.93 mmol, 1 eq) in acetone (40 mL) at 25° C. was added K₂CO₃ (4.47 g, 32.33 mmol, 2.5 eq). The suspension was stirred for 0.5 h and followed by addition of MOM-Cl (2.79 mL, 36.76 mmol, 2.84 eq) dropwise. The mixture was stirred at 25° C. for 15 h before it was diluted with water (40 mL) and extracted with ethyl acetate (2×30 mL). The combined organic layer was washed with brine (50 mL), dried by Na₂SO₄, filtered and concentrated. The crude residue was purified by Combi-flash on silica gel (20-60% ethyl acetate in petroleum ether) to provide 3-bromo-1-(methoxy-methyl)-pyridin-2 (1H)-one (1.22 g, 43% yield) as a clear oil.

Step 2:

To a solution of 3-bromo-1-(methoxymethyl)pyridin-2 (1H)-one (1.38 g, 6.33 mmol, 1 eq) and (4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)methanol (1.06 g, 6.96 mmol, 1.1 eq) in dioxane (12 mL) was added K₂CO₃ (2.62 g, 18.99 mmol, 3 eq), Pd(dppf)Cl₂ (463 mg, 632.89 umol, 0.1 eq) and H₂O (4 mL). The mixture was de-gassed with N₂ for 10 min before it was then heated at 80° C. for 16 h under N₂ atmosphere. The reaction was diluted with water (10 mL) and extracted with ethyl acetate (3×10 mL). The combined organic layer was washed with brine (25 mL), dried by Na₂SO₄, filtered and concentrated. The crude residue was purified by Combi-flash on silica gel (50-100% ethyl acetate in petroleum ether) to provide 3-(4-(hydroxymethyl)phenyl)-1-(methoxymethyl)pyridin-2 (1H)-one (1.30 g, 84% yield) as a yellow gum.

Step 3:

To a solution of PPh₃ (8.34 g, 31.80 mmol, 6 eq) in DCM (50 mL) at −25° C. was added CBr₄ (10.55 g, 31.80 mmol, 6 eq). The yellow suspension was stirred at −25° C. for 1 h and followed by addition of a solution of 3-(4-(hydroxymethyl)phenyl)-1-(methoxymethyl)-pyridin-2 (1H)-one (1.30 g, 5.30 mmol, 1 eq) in DCM (10 mL) dropwise. The yellow suspension was stirred at −25° C. for 0.5 h before it was diluted with MTBE (180 mL). The precipitate was filtered off and the filtrate was concentrated to give crude (2.8 g) as a yellow gum. The crude residue was purified by Combi-flash on silica gel (30-100% ethyl acetate in petroleum ether) to provide 3-(4-(bromomethyl)phenyl)-1-(methoxymethyl)-pyridin-2 (1H)-one (760 mg, 46% yield) as a white solid.

Step 4:

To a solution of diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-N,N′-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)-methoxy)-malonate (100 mg, 130.18 umol, 1 eq) in DMF (1.5 mL) at 20° C. was added K₂CO₃ (53.97 mg, 390.54 umol, 3 eq). The suspension was stirred for 0.5 h and followed by addition of 3-(4-(bromomethyl)phenyl)-1-(methoxymethyl)pyridin-2 (1H)-one (44.13 mg, 143.20 umol, 1.1 eq). The suspension was stirred at 20° C. for 16 h before it was diluted with water (2 mL) and extracted with ethyl acetate (3×2 mL). The combined organic layer was dried by Na₂SO₄, filtered and concentrated. The crude residue was purified by preparative TLC (petroleum ether:ethyl acetate=1:1) to provide diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-(N,N′-bis-(tert-butoxy-carbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydro-furan-2-yl)methoxy)-2-(4-(1-(methoxymethyl)-2-oxo-1,2-dihydropyridin-3-yl)benzyl)-malonate (71 mg, 55% yield) as a clear syrup.

Step 5:

To a solution of diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-(N,N′-bis-(tert-butoxy-carbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)-methoxy)-2-(4-(1-(methoxymethyl)-2-oxo-1,2-dihydropyridin-3-yl)benzyl)-malonate (68 mg, 68.31 umol, 1 eq) in DCM (1.7 mL) at 0° C. was added TFA (0.3 mL, 4.05 mmol, 59 eq). The mixture was stirred at 20° C. for 2 h before it was quenched with saturated aq. NaHCO₃ solution to adjust the pH to 9. The mixture was extracted with ethyl acetate (3×8 mL). The combined organic layer was concentrated to give crude (98 mg) as a yellow gum. The crude residue was purified by preparative TLC (ethyl acetate) to provide diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)-methoxy)-2-(4-(1-(methoxymethyl)-2-oxo-1,2-dihydropyridin-3-yl)benzyl)-malonate (21 mg, 38% yield) as a colorless syrup.

Step 6:

To a solution of diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-2-(4-(1-(methoxy-methyl)-2-oxo-1,2-dihydropyridin-3-yl)benzyl)malonate (20 mg, 25.15 umol, 1 eq) in THF (1 mL) was added 1M aq. LiOH (503 uL, 20 eq). The mixture was stirred at 18° C. for 22 h before it was acidified to pH 2 with 1N aq. HCl and concentrated. The crude residue was purified by preparative HPLC and the fraction was dried by lyophilization to provide the title compound (2.1 mg, 13% yield) as a white solid.

¹H NMR (400 MHz, DMSO-d₆) δ ppm 8.45 (br s, 1H), 7.81 (br s, 2H), 7.67 (dd, J=6.75, 1.75 Hz, 1H), 7.51 (br d, J=6.75 Hz, 1H), 7.36 (br d, J=6.88 Hz, 2H), 7.20 (br d, J=7.50 Hz, 2H), 6.33 (t, J=6.75 Hz, 1H), 6.20 (br s, 1H), 6.01 (br d, J=6.88 Hz, 1H), 5.82 (d, J=7.50 Hz, 1H), 5.28 (s, 2H), 4.65-4.89 (m, 1H), 4.06-4.23 (m, 1H) 3.88-4.06 (m, 1H), 3.67-3.86 (m, 1H), 3.40-3.52 (m, 3H), 3.18-3.30 (m, 2H); LC/MS [M+H]=655.1.

Example 12 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxo-1,2-dihydropyridin-3-yl)benzyl)malonic acid

Step 1:

To a solution of diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-N,N′-(bis-(tert-butoxy-carbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)-methoxy)-malonate (12.59 g, 16.39 mmol, 1 eq) and 1-(bromomethyl)-4-iodo-benzene (48.67 g, 163.90 mmol, 10 eq) in DMF (120 mL) at 20° C. was added K₂CO₃ (33.98 g, 245.85 mmol, 15 eq). The solution was stirred for 16 h before it was diluted with water (200 mL) and extracted with ethyl acetate (3×200 mL). The combined organic layer was washed with water (400 mL), brine (400 mL), dried by Na₂SO₄, filtered and concentrated. The crude residue was purified by Combi-flash on silica gel (15-40% ethyl acetate in petroleum ether) to give diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-N,N′-(bis-(tert-butoxycarbonyl)-amino)-2-chloro-9H-purin-9-yl)-3-ethynyltetra-hydrofuran-2-yl)methoxy)-2-(4-iodobenzyl)-malonate (2.94 g, 18% yield) as a yellow solid.

Step 2:

To a solution of diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-N,N′-(bis-(tert-butoxy-carbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)-methoxy)-2-(4-iodobenzyl)malonate (1.10 g, 1.12 mmol, 1 eq) and (2-oxo-1,2-dihydropyridin-3-yl)boronic acid (310.53 mg, 2.24 mmol, 2 eq) in dioxane (12 mL) was added K₂CO₃ (463.41 mg, 3.35 mmol, 3 eq), Pd(dppf)Cl₂ (81.78 mg, 111.77 umol, 0.1 eq) and H₂O (4 mL). The mixture was degassed with N₂ for 10 min and then stirred at 80° C. for 1 h under N₂ atmosphere. The dark mixture was diluted with water (10 mL) and extracted with ethyl acetate (3×10 mL). The combined organic layer was washed with brine (30 mL), dried by Na₂SO₄, filtered and concentrated. The crude residue was purified by Combi-flash on silica gel (40-100% ethyl acetate in petroleum ether) to give diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-N,N′-(bis-(tert-butoxy-carbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)-methoxy)-2-(4-(2-oxo-1,2-dihydropyridin-3-yl)benzyl)malonate (220 mg, 21% yield) as a yellow gum.

Step 3:

To a solution of diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-N,N′-(bis-(tert-butoxy-carbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)-methoxy)-2-(4-(2-oxo-1,2-dihydropyridin-3-yl)benzyl)malonate (180 mg, 189.20 umol, 1 eq) in DCM (2.4 mL) was added TFA (0.6 mL, 8.10 mmol, 43 eq). The yellow solution was stirred at 20° C. for 2.5 h before it was quenched with saturated aq. NaHCO₃ (5 mL) and extracted with ethyl acetate (3×4 mL). The combined organic layer was concentrated to give crude (108 mg) as a yellow gum. The crude residue was purified by preparative TLC (ethyl acetate) to give diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyltetra-hydrofuran-2-yl)methoxy)-2-(4-(2-oxo-1,2-dihydropyridin-3-yl)benzyl)-malonate (23 mg, 16% yield) as a yellow solid.

Step 4:

To a solution of diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxo-1,2-dihydropyridin-3-yl)benzyl)malonate (23 mg, 30.62 umol, 1 eq) in THF (2.5 mL) was added 1M aq. LiOH (0.6 mL, 20 eq). The reaction mixture was stirred at 20° C. for 4 h before it was acidified to pH 6 with 1N aq. HCl and concentrated to give crude (32 mg) as a yellow gum. The crude residue was purified by preparative HPLC (column: YMC-Triart Prep C18 150*40 mm*7 um; Mobile phase: [water (0.225% FA)-CAN]; B %: 15%-35%, 10 min). The product was dried by lyophilization to give the title compound (2.1 mg, 11% yield) as a white solid.

¹H NMR (400 MHz, CD3OD) δ ppm 8.24 (s, 1H), 7.46 (dd, J=6.88, 1.63 Hz, 1H), 7.28-7.34 (m, 5H), 6.39 (t, J=6.75 Hz, 1H), 5.96 (d, J=7.38 Hz, 1H), 4.77-4.84 (m, 1H), 4.29 (t, J=2.88 Hz, 1H), 4.03 (d, J=2.75 Hz, 2H), 3.38-3.51 (m, 2H), 3.04 (s, 1H); LC/MS [M+H]=611.0.

Example 13 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-((2-carboxy-[1,1′-biphenyl]-4-yl)methyl)malonic acid

Step 1:

To a mixture of diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-N,N′-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-malonate (99.87 mg, 130.01 umol, 1 eq) in DMF (0.5 mL) was added K₂CO₃ (53.90 mg, 390.03 umol, 3 eq). The mixture was stirred at 40° C. for 0.5 h and followed by addition of methyl 4-(bromomethyl)-[1,1′-biphenyl]-2-carboxylate (79.35 mg, 260.02 umol, 2 eq) which was prepared according to the reported procedure by D. Stoermer et al (J. of Med. Chem. 2012, 55, 5922-5932). The mixture was stirred at 40° C. for 15.5 h before it was diluted with water (4 mL) and extracted with EtOAc (3×5 mL). The combined organic layer was washed with water (2×5 mL) and brine (5 mL), dried over anhydrous Na₂SO₄, filtered and concentrated. The crude residue was purified by preparative TLC (petroleum ether:EtOAc=1:1) to give diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-N,N′-(bis-(tert-butoxycarbonyl)-amino)-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-2-((2-(methoxy-carbonyl)-[1,1′-biphenyl]-4-yl)methyl)malonate (70 mg, 53% yield) as a colorless syrup.

Step 2:

To a solution of diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-N,N′-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-2-((2-(methoxycarbonyl)-[1,1′-biphenyl]-4-yl)methyl)malonate (70 mg, 70.53 umol, 1 eq) in DCM (2 mL) was added TFA (0.5 mL, 6.75 mmol, 96 eq). The mixture was stirred at 20° C. for 2 h before it was quenched with saturated aq. NaHCO₃ to pH 7-8 and extracted with EtOAc (3×10 mL). The combined organic layer was washed with water (2×8 mL) and brine (8 mL), dried over anhydrous Na₂SO₄, filtered and concentrated. The crude residue was purified by preparative TLC (petroleum ether:EtOAc=1:1) to give diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydro-furan-2-yl)-methoxy)-2-((2-(methoxycarbonyl)-[1,1′-biphenyl]-4-yl)methyl)malonate (40 mg, 71% yield) as a colorless syrup.

Step 3:

To a solution of diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-2-((2-(methoxy-carbonyl)-[,1′-biphenyl]-4-yl)methyl)malonate (30 mg, 37.87 umol, 1 eq) in THF (1 mL) was added 1M aq. LiOH (568 uL, 15 eq). The mixture was stirred at 25° C. for 20 h before it was diluted with water (1 mL) and extracted with EtOAc (3×2 mL). The organic layer was discarded. The pH of the water phase was adjusted to 2 with 2N aq. HCl to produce a precipitate. The precipitate was collected by filtration to give desired product (28 mg) as the first crop. The aq. phase was further extracted with EtOAc (4×2 mL). The combined organic layer was dried over anhydrous Na₂SO₄, filtered and concentrated to provide the second crop (10 mg) as a white solid. These two crops were combined and purified by preparative HPLC and the fraction was lyophilized to give the title compound (8.0 mg, 33% yield) as a white solid.

¹H NMR (400 MHz, CD3OD) δ ppm 8.21 (s, 1H), 7.66 (s, 1H), 7.46 (br d, J=7.6 Hz, 1H), 7.24-7.32 (m, 3H), 7.12 (dd, J=7.1, 2.3 Hz, 2H), 7.07 (d, J=7.9 Hz, 1H), 5.99 (d, J=7.4 Hz, 1H), 4.84 (br s, 1H), 4.33 (br s, 1H), 4.02-4.16 (m, 2H), 3.43-3.60 (m, 2H), 3.03 (s, 1H); LC/MS [M+H]=638.2.

Example 14 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-phenyl-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

Step 1:

To a solution of 2,6-dichloroadenine (0.8 g, 4.23 mmol, 1 eq) in H₂O (10 mL) and MeCN (5 mL) was added phenylboronic acid (464.49 mg, 3.81 mmol, 0.9 eq), Cs₂CO₃ (3.45 g, 10.58 mmol, 2.5 eq), Pd(OAc)₂ (47.51 mg, 211.64 umol, 0.05 eq) and trisodium; 3-bis(3-sulfonatophenyl)phosphanylbenzenesulfonate (601.50 mg, 1.06 mmol, 0.25 eq) at 20° C. under N₂ atmosphere. The mixture was stirred at 110° C. for 2 h before it was allowed to cool and diluted with H₂O (50 mL). The reaction mixture was extracted with EtOAc (5×50 mL). The combined organic layer was washed with brine (50 mL), dried over Na₂SO₄, filtered and concentrated. The crude product was triturated with a mixture of petroleum ether (9 mL) and EtOAc (3 mL) to provide 2-chloro-6-phenyl-9H-purine (140 mg, 14% yield) as a yellow solid.

Step 2:

To a solution of 2-chloro-6-phenyl-9H-purine (321.05 mg, 585.30 umol, 1 eq) in MeCN (0.5 mL) was added diethyl 2-benzyl-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-ethynyltetra-hydrofuran-2-yl)methoxy)malonate (135 mg, 585.30 umol, 1 eq) and BSA (347 uL, 1.40 mmol, 2.4 eq) at 15° C. The mixture was stirred at 65° C. for 30 min as it became clear. The mixture was cooled to 0° C. and followed by dropwise addition of TMSOTf (126.91 uL, 702.35 umol, 1.2 eq). The mixture was stirred for 0° C. 10 min and then at 65° C. for 3 h before it was cooled and quenched with saturated aq. NaHCO₃ (40 mL). The reaction mixture was extracted with EtOAc (2×30 mL). The combined organic layer was washed with brine (40 mL) and dried over Na₂SO₄, filtered and concentrated. The crude product was purified by flash silica gel column chromatography (petroleum:EtOAc=1:0-1:1) first and then by preparative TLC (petroleum:EtOAc=1:1) to provide diethyl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(2-chloro-6-phenyl-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (135 mg) as a yellow gum.

Step 3:

To a solution of diethyl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(2-chloro-6-phenyl-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (135 mg, 187.73 umol, 1 eq) in THF (2 mL) was added LiOH·H₂O (78.77 mg, 1.88 mmol, 10 eq) in H₂O (0.2 mL) at 20° C. The mixture was stirred at 45° C. for 2 h before it was diluted with H₂O (10 mL) and with EtOAc (2 mL). The organic layer was discarded and the aqueous phase was acidified with 2N aq. HCl to pH 2-3. Then the aqueous phase was extracted with EtOAc (3×20 mL). The combined organic layer was washed with brine (30 mL), dried over Na₂SO₄, filtered and concentrated. The crude product was purified by preparative HPLC to provide the title compound (27.6 mg, 24% yield) as a white solid.

¹H NMR (400 MHz, DMSO-d₆) δ ppm 9.23 (s, 1H), 8.75-8.81 (m, 2H), 7.61-7.68 (m, 3H), 7.07-7.22 (m, 5H), 6.03 (d, J=6.53 Hz, 1H), 4.62 (d, J=6.53 Hz, 1H), 4.20 (dd, J=6.90, 2.64 Hz, 1H), 3.72 (br dd, J=9.91, 7.15 Hz, 2H), 3.55 (s, 1H), 3.03 (br d, J=1.51 Hz, 2H); LC/MS [M+H]=579.1.

Example 15 Synthesis of 2-allyl-2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

Step 1:

To a solution of diethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-6-ethynyl-2,2-dimethyltetra-hydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)malonate (600 mg, 1.45 mmol, 1 eq) in DMF (1 mL) was added allyl bromide (263 mg, 2.17 mmol, 1.5 eq) and Cs₂CO₃ (943 mg, 2.90 mmol, 2 eq). The mixture was stirred at 20° C. for 2 h before it was diluted with water (15 mL) and extracted with EtOAc (4×10 mL). The combined organic phase was washed with water (10 mL), brine (10 mL), dried over anhydrous Na₂SO₄, filtered and concentrated to provide crude diethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-6-ethynyl-2,2-dimethyltetrahydro-furo[2,3-d][1,3]-dioxol-5-yl)methoxy)-2-allylmalonate (685 mg) as a colorless gum.

Step 2:

To a solution of crude diethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-6-ethynyl-2,2-dimethyltetrahydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)-2-allylmalonate (685 mg, 1.51 mmol, 1 eq) in DCM (5 mL) was added TFA (5 mL, 67.53 mmol, 45 eq) and H₂O (1 mL, 55.51 mmol, 37 eq). The mixture was stirred at 20° C. for 16 h before it was diluted with water (15 mL) and adjusted the pH to 7-8 with solid NaHCO₃. The reaction mixture was extracted with a mixture of DCM and MeOH (4×12 mL; 10:1/v:v). The combined extract was washed with saturated aq. NaHCO₃ (8 mL), brine (8 mL), dried over anhydrous Na₂SO₄, filtered and concentrated under reduced pressure to give crude diethyl 2-(((2R,3S,4R)-3-acetoxy-3-ethynyl-4,5-dihydroxytetrahydrofuran-2-yl)methoxy)-2-allylmalonate (580 mg) as a yellow gum.

Step 3:

To a solution of crude diethyl 2-(((2R,3S,4R)-3-acetoxy-3-ethynyl-4,5-dihydroxytetra-hydrofuran-2-yl)methoxy)-2-allylmalonate (580 mg, 1.40 mmol, 1 eq) in pyridine (5 mL) was added Ac₂O (1.31 mL, 14.00 mmol, 10 eq) and 4-DMAP (513 mg, 4.20 mmol, 3 eq). The mixture was stirred at 20° C. for 15 before it was diluted with water (15 mL) and extracted with EtOAc (3×10 mL). The combined extract was washed with 0.5 N aq. HCl (2×8 mL), NaHCO₃ (2×8 mL), brine (8 mL), dried over anhydrous Na₂SO₄, filtered and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography (petroleum ether:EtOAc=5:1-2:1) to give (420 mg, 60% yield) as a colorless gum.

Step 4:

To a mixture of diethyl 2-allyl-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-ethynyltetra-hydrofuran-2-yl)methoxy)malonate (360 mg, 722.20 umol, 1 eq) and 2-chloro-9H-purin-6-amine (135 mg, 794.42 umol, 1.1 eq) in MeCN (5 mL) was added BSA (446.28 uL, 1.81 mmol, 2.5 eq) at 25° C. under N₂ atmosphere. The mixture was stirred at 65° C. for 0.5 h. The reaction mixture was cooled to 0° C. and followed by dropwise addition of TMSOTf (261.00 uL, 1.44 mmol, 2 eq) in MeCN (1 mL). The mixture was stirred at 65° C. for 3 h before it was allowed to cooled and quenched with saturated aq. NaHCO₃ solution (15 mL). Then the mixture was extracted with EtOAc (4×10 mL), washed with saturated brine (8 mL), dried over anhydrous Na₂SO₄, filtrated and concentrated. The crude product was purified by Combi-flash on silica gel (20-40% EtOAc in petroleum ether) to give diethyl 2-allyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyltetra-hydrofuran-2-yl)methoxy)malonate (190 mg) as a colorless gum.

Step 5:

To a solution of diethyl 2-allyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (100 mg, 164.47 umol, 1 eq) in THF (0.5 mL) was added LiOH·H₂O (6.90 mg, 164.47 umol, 1 eq). The mixture was stirred at 50° C. for 1 h before it was diluted with water (6 mL) and extracted with EtOAc (3×4 mL). The organic layer was discarded. The pH of the aq. phase was adjusted to 2 with 2N aq. HCl solution. The aq. phase was then extracted with EtOAc (4×6 mL). The combined organic phases was washed with brine (6 mL), dried over anhydrous Na₂SO₄, filtered and concentrated to provide a solid. The solid was dissolved in a mixture of MeCN (1 mL) and water (1 mL) and then lyophilizied directly to give the title compound (65.2 mg, 83% yield) as a white solid.

¹H NMR (400 MHz, CD3OD) δ ppm 8.83 (s, 1H) 6.05 (d, J=7.5 Hz, 1H) 5.84 (br dd, J=17.2, 10.2 Hz, 1H) 5.15 (dd, J=17.2, 1.6 Hz, 1H) 4.99-5.05 (m, 2H) 4.27 (t, J=2.5 Hz, 1H) 4.00 (dd, J=10.2, 2.6 Hz, 1H) 3.79 (dd, J=10.3, 2.8 Hz, 1H) 3.06 (s, 1H) 2.88 (d, J=7.3 Hz, 2H); LC/MS [M+H]=467.9.

Example 16 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-ethylmalonic acid

Proceeding as described in Example 15 above but substituting allyl bromide with EtBr provided the title compound as a white solid.

¹H NMR (400 MHz, DMSO-d₆) δ ppm 8.53-8.83 (m, 1H) 7.81 (br s, 2H) 5.91-6.40 (m, 2H) 5.83 (d, J=7.88 Hz, 1H) 4.91 (d, J=7.75 Hz, 1H) 4.14 (t, J=2.88 Hz, 1H) 3.75 (dd, J=10.26, 3.25 Hz, 1H) 3.56 (s, 1H) 3.47-3.51 (m, 1H) 1.93-2.04 (m, 2H) 0.76 (t, J=7.38 Hz, 3H); LC/MS [M+H]=455.9.

Example 17 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-methylmalonic acid

Proceeding as described in Example 15 above but substituting allyl bromide with methyl bromide provided the title compound as a white solid.

¹H NMR (400 MHz, DMSO-d₆) δ ppm 13.38 (br s, 2H) 8.69 (s, 1H) 7.82 (br s, 2H) 6.17 (br s, 1H) 5.98 (br d, J=7.25 Hz, 1H) 5.82 (d, J=7.63 Hz, 1H) 4.85 (br t, J=6.94 Hz, 1H) 4.15 (t, J=2.75 Hz, 1H) 3.83 (dd, J=10.13, 3.25 Hz, 1H) 3.53-3.65 (m, 2H) 1.52 (s, 3H); LC/MS [M+H]=441.8.

Example 18 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-(thiophen-2-yl)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

Step 1:

To a mixture of 2-chloroadenine (800 mg, 4.23 mmol, 1 eq) in MeCN (5 mL) and H₂O (10 mL) at 20° C. under N₂ atmosphere was added 4,4,5,5-tetramethyl-2-(thiophen-2-yl)-1,3,2-dioxaborolane (800.37 mg, 3.81 mmol, 0.9 eq), Pd(OAc)₂ (47.51 mg, 211.64 umol, 0.05 eq), Cs₂CO₃ (3.45 g, 10.58 mmol, 2.5 eq) and triphenylphosphine-3,3′-3″-trisulfonic acid trisodium salt (601.50 mg, 1.06 mmol, 0.25 eq). The mixture was stirred at 110° C. for 3 h before it was allowed to cool and partitioned between EtOAc (3×20 mL) and H₂O (10 mL). The combined organic phase was washed with H₂O (2×10 mL), dried over Na₂SO₄, filtered and concentrated under reduced pressure. The crude product was triturated with (petroleum ether:EtOAc=3:1) and left standing for for 14 h. The precipitate was collected by suction filtration and dried to provide 2-chloro-6-(thiophen-2-yl)-9H-purine (190 mg, 19% yield) as a yellow solid.

Step 2:

To a mixture of 2-chloro-6-(thiophen-2-yl)-9H-purine (140 mg, 591.51 umol, 1 eq) and diethyl 2-benzyl-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (324.47 mg, 591.51 umol, 1 eq) in MeCN (3 mL) at 0° C. was added DBU (267 uL, 1.77 mmol, 3 eq). The mixture was stirred at 0° C. for 10 min and followed by dropwise addition of TMSOTf (481 uL, 2.66 mmol, 4.5 eq). The mixture was stirred at 0° C. for 30 min and then at 65° C. under N₂ atmosphere for 14 h. The reaction mixture was allowed to cool and partitioned between EtOAc (3×20 mL) and saturated aq. NaHCO₃ (2×10 mL). The combined organic phase was washed with brine (2×20 mL), dried over Na₂SO₄, filtered and concentrated. The crude product was purified by preparative TLC (petroleum ether:EtOAc=2:1) to provide diethyl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(2-chloro-6-(thiophen-2-yl)-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-malonate (150 mg, 31% yield) as a white solid.

Step 3:

To a mixture of diethyl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(2-chloro-6-(thiophen-2-yl)-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (150 mg, 206.85 umol, 1 eq) in THF (2 mL) was added LiOH·H₂O (2 M, 2 mL, 19.34 eq). The mixture was stirred at 25° C. for 2 h before it was partitioned between EtOAc (10 mL) and water (10 mL). The aqueous phase was adjusted to pH˜2 with 2M aq. HCl solution. The aqueous phase was partitioned between EtOAc (40 mL) and brine (20 mL), dried over anhydrous Na₂SO₄, filtered and concentrated under reduced pressure. The crude product was purified by preparative HPLC (column: YMC-Triart Prep C18 150*40 mm*7 um; mobile phase: [water (0.225% FA)-ACN]; B %: 43%-63%, 10 min) and lyophilized to provide the title compound (31.6 mg, 26% yield) as a white solid.

¹H NMR (400 MHz, DMSO-d₆) δ ppm 8.87 (s, 1H) 8.60 (dd, J=3.76, 1.25 Hz, 1H) 8.02 (dd, J=5.02, 1.00 Hz, 1H) 7.36 (dd, J=4.89, 3.89 Hz, 1H) 7.16-7.28 (m, 2H) 6.93-7.10 (m, 3H) 6.31 (br s, 1H) 6.11 (br d, J=6.02 Hz, 1H) 5.99 (d, J=7.53 Hz, 1H) 4.88-4.97 (m, 1H) 4.23 (dd, J=4.27, 2.76 Hz, 1H) 3.99 (br dd, J=10.42, 4.39 Hz, 1H) 3.84 (br d, J=8.53 Hz, 1H) 3.56 (s, 1H) 3.26 (s, 2H); LC/MS [M+H]=585.0.

Example 19 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxo-1-propyl-1,2-dihydropyridin-3-yl)benzyl)malonic acid

Step 1:

To a solution of 3-bromopyridin-2 (1H)-one (3 g, 17.24 mmol, 1 eq) in acetone (100 mL) was added K₂CO₃ (11.91 g, 86.21 mmol, 5 eq). The suspension was stirred at 20° C. for 0.5 h and followed by addition of 1-bromopropane (4.71 mL, 51.73 mmol, 3 eq) and KI (859 mg, 5.17 mmol, 0.3 eq). The mixture was stirred at 20° C. for 16 h. Additional amount of 1-bromopropane (1.0 g) was added to the reaction mixture and the mixture was stirred further at 20° C. for 3 h. The reaction was diluted with water (50 mL) and extracted with EtOAc (3×40 mL). The combined organic layer was washed with brine (100 mL), and dried over anhydrous Na₂SO₄, filtered and concentrated. The residue was purified by Combi-Flash (silica gel, 20-60% EtOAc in petroleum ether) to provide 3-bromo-1-propylpyridin-2 (1H)-one (1.23 g, 33% yield) as a clear oil.

Step 2:

To a solution of 3-bromo-1-propylpyridin-2 (1H)-one (1.79 g, 8.28 mmol, 1 eq) and (4-(hydroxymethyl)phenyl)boronic acid (1.38 g, 9.11 mmol, 1.1 eq) in dioxane (18 mL) was added K₂CO₃ (3.43 g, 24.84 mmol, 3 eq), Pd(dppf)Cl₂ (606 mg, 828.00 umol, 0.1 eq) and H₂O (6 mL). The mixture was degassed with N₂ for 10 min and then stirred at 80° C. for 16 h under N₂ atmosphere. The reaction mixture was cooled and filtered. The filtrate was concentrated. The residue was purified by Combi Flash (silica gel, 30-50% of EtOAc in petroleum ether) to provide 3-(4-(hydroxymethyl)phenyl)-1-propylpyridin-2 (1H)-one (1.84 g, 910% yield) as a brown solid.

Step 3:

To a solution of PPh₃ (1.94 g, 7.40 mmol, 6 eq) in DCM (15 mL) was added CBr₄ (2.45 g, 7.40 mmol, 6 eq) at −25° C. The yellow solution was stirred at −25° C. for 1 h and followed by addition of 3-(4-(hydroxymethyl)phenyl)-1-propylpyridin-2 (1H)-one (300 mg, 1.23 mmol, 1 eq) in DCM (3 mL) dropwise. The yellow suspension was stirred at −25° C. for 0.5 h to produce a yellow suspension. The reaction mixture was diluted with MTBE (50 mL) to produce more precipitate. The precipitate was filtered off and the filtrate was concentrated. The residue was purified by CombiFlash (silica gel column, 10-100% of EtOAc in petroleum ether) to provide 3-(4-(bromomethyl)phenyl)-1-propylpyridin-2 (1H)-one (243 mg, 64% yield) as a clear oil.

Step 4:

To a solution of diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-N,N′-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-malonate (554 mg, 721.20 umol, 1 eq) in DMF (5 mL) was added K₂CO₃ (299.03 mg, 2.16 mmol, 3 eq). The mixture was stirred at 20° C. for 0.5 h and followed by addition of 3-(4-(bromomethyl)phenyl)-1-propylpyridin-2 (1H)-one (242.91 mg, 793.32 umol, 1.1 eq). The mixture was stirred at 20° C. for 16 h before it was diluted with water (30 mL) and extracted by EtOAc (4×20 mL). The combined organic layer was washed with water (100 mL), dried over anhydrous Na₂SO₄, filtered and concentrated. The residue was purified by Combi Flash (silica gel, 20-30% of EtOAc in petroleum ether to provide diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-N,N′-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyl-tetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxo-1-propyl-1,2-dihydropyridin-3-yl)benzyl)-malonate (209 mg) as a colorless gum.

Step 5:

To a solution of diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-N,N′-(bis-(tert-butoxy-carbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxo-1-propyl-1,2-dihydropyridin-3-yl)benzyl)malonate (209 mg, 210.38 umol, 1 eq) in DCM (2 mL) at 0° C. was added TFA (0.7 mL, 9.45 mmol, 44.94 eq). The solution was stirred at 20° C. for 2 h before it was quenched by saturated aq. NaHCO₃ (5 mL) and extracted with EtOAc (4×10 mL). The combined organic layer was dried over anhydrous Na₂SO₄, filtered and concentrated. The residue was purified by Combi Flash (silica gel, 30-70% of EtOAc in petroleum ether) to provide diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxo-1-propyl-1,2-dihydro-pyridin-3-yl)benzyl)malonate (91 mg, 55% yield) as a white solid.

Step 6:

To a solution of diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxo-1-propyl-1,2-dihydro-pyridin-3-yl)benzyl)malonate (91 mg, 114.72 umol, 1 eq) in THF (1 mL) was added 1N aq. LiOH (1 mL). The mixture was stirred at 20° C. for 2.5 h before it was diluted with water (5 mL) and the resulting solution was washed with EtOAc (2×10 mL). The organic extract was discarded. The aqueous layer acidified to pH 2 with 2N aq. HCl and then extracted with EtOAc (4×8 mL). The combined organic layer was dried over anhydrous Na₂SO₄, filtered and concentrated. The residue was dissolved in a mixture of MeOH (5 mL) and water (20 mL) and was dried by lyophilization to provide the title compound (51 mg, 67% yield) as a white solid.

¹H NMR (400 MHz, CD3OD) δ ppm 8.08 (s, 1H), 7.53 (dd, J=6.80, 2.0 Hz, 1H), 7.28-7.39 (m, 5H), 6.34 (t, J=6.9 Hz, 1H), 5.96 (d, J=7.6 Hz, 1H), 4.77 (d, J=7.6 Hz, 1H), 4.28 (s, 1H), 4.07-4.15 (m, 1H), 4.01 (dd, J=10.3, 2.8 Hz, 1H), 3.92 (t, J=7.4 Hz, 2H), 3.39-3.58 (m, 2H), 3.06 (s, 1H), 1.65-1.80 (m, 2H), 0.94 (t, J=7.4 Hz, 3H); LC/MS [M+H]=653.1.

Example 20 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(1-ethyl-2-oxo-1,2-dihydropyridin-3-yl)benzyl)malonic acid

Proceeding as described in Example 19 above but substituting propyl bromide with ethyl bromide provided the title compound as a white solid.

¹H NMR (400 MHz, CD3OD) δ ppm 8.15 (s, 1H), 7.53 (dd, J=6.6, 1.3 Hz, 1H), 7.25-7.38 (m, 5H), 6.32 (t, J=6.9 Hz, 1H), 5.96 (d, J=7.6 Hz, 1H), 4.78 (d, J=7.5 Hz, 1H), 4.30 (s, 1H), 4.09-4.15 (m, 1H), 3.95-4.04 (m, 3H), 3.39-3.58 (m, 2H), 3.06 (s, 1H), 1.28-1.32 (m, 3H); LC/MS [M+H]=639.1.

Example 21 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(1-(2-hydroxyethyl)-2-oxo-1,2-dihydropyridin-3-yl)benzyl)malonic acid

Step 1:

To a mixture of 3-bromopyridin-2 (1H)-one (3 g, 17.24 mmol, 1 eq) in acetone (100 mL) at 20° C. was added KI (859 mg, 5.17 mmol, 0.3 eq), K₂CO₃ (5.96 g, 43.10 mmol, 2.5 eq) and 2-bromoethanol (4.90 mL, 68.97 mmol, 4 eq). The mixture was stirred for 4 before it was filtered and the filter cake was washed with EtOAc (100 mL). The filtrate was concentrated under reduced pressure to give a residue. The residue was purified by flash silica gel column chromatography (petroleum ether:EtOAc=5:1 to 0:1) to provide 3-bromo-1-(2-hydroxyethyl)pyridin-2 (1H)-one (2.2 g, 59% yield) as a yellow gum.

Step 2:

To a mixture of 3-bromo-1-(2-hydroxyethyl)pyridin-2 (1H)-one (2.2 g, 10.09 mmol, 1 eq) in DMF (15 mL) at 20° C. was added imidazole (1.72 g, 25.22 mmol, 2.5 eq) and TBDPSCl (5.18 mL, 20.18 mmol, 2 eq). The mixture was stirred for 2 h before it was diluted with H₂O (60 mL) and extracted with EtOAc (3×30 mL). The combined extract was washed with saturated aq. NH₄Cl (2×30 mL), brine (30 mL), dried over anhydrous Na₂SO₄, filtered and concentrated under reduced pressure. The residue was purified by flash silica gel column chromatography (petroleum ether:EtOAc=1:0 to 6:1) to provide 3-bromo-1-(2-((tert-butyldiphenylsilyl)oxy)ethyl)-pyridin-2 (1H)-one (3.75 g, 79% yield) as a light yellow oil.

Steps 3-8:

Proceeding as described in Example 19 above but substituting 3-(4-(bromomethyl)-phenyl)-1-propylpyridin-2 (1H)-one with 3-bromo-1-(2-((tert-butyldiphenylsilyl)oxy)ethyl)-pyridin-2 (1H)-one provided the title compound as a white solid.

¹H NMR (400 MHz, CD3OD) δ ppm 8.33 (s, 1H), 7.50-7.57 (m, 1H), 7.41-7.47 (m, 1H), 7.39 (d, J=8.13 Hz, 2H), 7.29 (br d, J=8.13 Hz, 2H), 6.35 (t, J=6.88 Hz, 1H), 5.98 (d, J=7.13 Hz, 1H), 4.71 (d, J=7.00 Hz, 1H), 4.30 (br s, 1H), 3.93-4.16 (m, 4H), 3.83 (m, 2H), 3.36-3.50 (m, 2H), 3.05 (s, 1H); LC/MS [M+H]=655.1.

Example 22 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(2-methoxypyridin-3-yl)benzyl)malonic acid

Step 1:

To a solution of diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-N,N′-(bis-(tert-butoxy-carbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)-methoxy)-2-(4-iodobenzyl)malonate (900 mg, 914.47 umol, 1 eq) and (2-methoxy-3-pyridyl)boronic acid (168 mg, 1.10 mmol, 1.2 eq) in dioxane (9 mL) 25° C. was added K₂CO₃ (379 mg, 2.74 mmol, 3 eq), Pd(dppf)Cl₂ (67 mg, 91.45 umol, 0.1 eq) and H₂O (3 mL). The mixture was degassed with N₂ for a while and then heated to 80° C. for 16 h before it was diluted with water (10 mL), and extracted with ethyl acetate (2×10 mL). The combined organic layer was dried by Na₂SO₄, filtered and concentrated. The crude product was purified by Combi-flash (silica gel, 10-50% of EtOAc in petroleum ether) to give diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-N,N′-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydro-furan-2-yl)-methoxy)-2-(4-(2-methoxypyridin-3-yl)benzyl)malonate (117 mg, 13% yield) as a yellow gum.

Step 2:

To a solution of diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-N,N′-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)-methoxy)-2-(4-(2-methoxypyridin-3-yl)benzyl)malonate (90 mg, 93.23 umol, 1 eq) in DCM (3 mL) was added TFA (0.4 mL, 5.40 mmol, 58 eq). The solution was stirred at 20° C. for 2 h before it was quenched with saturated aq. NaHCO₃ (4 mL) and extracted with EtOAc (3×4 mL). The combined organic layer was concentrated to give crude diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-2-(4-(2-methoxypyridin-3-yl)benzyl)-malonate (42 mg) as a yellow gum.

Step 3:

To a solution of crude diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-2-(4-(2-methoxy-pyridin-3-yl)benzyl)malonate (42 mg, 54.89 umol, 1 eq) in THF (2.5 mL) was added 1M aq. LiOH (0.8 mL, 15 eq). The reaction mixture was stirred at 20° C. for 4 h before it was acidified to pH 6 with 1N aq. HCl and concentrated. The crude product was purified by preparative HPLC and the fraction was dried by lyophilization to give the title compound (6 mg, 17% yield) as a white solid.

¹H NMR (400 MHz, CD3OD) δ ppm 8.10 (s, 1H), 8.01 (dd, J=4.94, 1.69 Hz, 1H), 7.48 (dd, J=7.25, 1.63 Hz, 1H), 7.24-7.35 (m, 4H), 6.93 (dd, J=7.32, 5.07 Hz, 1H), 5.97 (d, J=7.50 Hz, 1H), 4.89-4.96 (m, 1H), 4.29 (br s, 1H), 4.05 (br d, J=5.00 Hz, 2H), 3.76 (s, 3H), 3.51 (br d, J=14.76 Hz, 1H), 3.42 (br d, J=14.51 Hz, 1H), 3.01 (s, 1H); LC/MS [M+H]=625.1.

Example 23 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(3-(trifluoromethoxy)benzyl)malonic acid

Proceeding as described in Example 1 above but substituting benzyl bromide with 1-(bromomethyl)-4-(trifluoromethoxy)benzene provided the title compound as a white solid.

¹H NMR (CD₃OD, 300 MHz) δ 8.43 (s, 1H), 7.09-7.25 (m, 3H), 6.95-6.98 (d, J=8.1 Hz, 1H), 6.01-6.04 (d, J=7.32 Hz, 1H), 5.00-5.03 (d, J=7.41 Hz, 1H), 4.35-4.37 (t, J=3.33 Hz, 1H), 4.05-4.15 (m, 2H), 3.38-3.53 (q, J=15 Hz, 2H), 2.99 (s, 1H); LC/MS [M+H]=602.0.

Example 24 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(thiophen-3-ylmethyl)malonic acid

Proceeding as described in Example 1 above but substituting benzyl bromide with 3-(bromomethyl)thiophene provided the title compound as a white solid.

¹H NMR (CD₃OD, 300 MHz) δ 8.39 (s, 1H), 7.09-7.17 (m, 2H), 6.98-7.00 (d, J=5.04.0 Hz, 1H), 6.01-6.04 (d, J=7.47 Hz, 1H), 5.00-5.02 (d, J=7.29 Hz, 1H), 4.32-4.34 (t, J=2.76 Hz, 1H), 4.01-4.11 (m, 2H), 3.41-3.54 (q, J=15 Hz, J=9.03 Hz, 2H), 2.98 (s, 1H); LC/MS [M+H]=524.0.

Example 25 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(prop-2-yn-1-yl)malonic acid

Proceeding as described in Example 1 above but substituting benzyl bromide with propargyl bromide provided the title compound as a white solid.

¹H NMR (CD₃OD, 300 MHz) δ 8.96 (s, 1H), 6.07-6.09 (d, J=7.53 Hz, 1H), 5.01-5.04 (d, J=7.53 Hz, 1H), 4.29-4.30 (m, 1H), 3.92-4.05 (m, 2H), 3.01-3.15 (m, 2H), 2.99 (s, 1H), 2.28-2.30 (t, J=2.58 Hz, 1H); LC/MS [M+H]=467.

Example 26 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

Step 1:

A solution of diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-N,N′-(bis-(tert-butoxy-carbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (200 mg, 0.26 mmol) in CH₂Cl₂ (1 mL) under argon atmosphere at 0° C. was added TFA (0.5 mL). The mixture was stirred for 5 minutes and allowed to warm up and stirred for 1 h. Additional amount of TFA (0.4 mL) was added to the reaction mixture and it was stirred further 1.5 h before it was concentrated. The residue was azeotroped with DCM (5×5 mL) under reduced pressure to provide crude diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydro-furan-2-yl)methoxy)malonate which was used in the next step without further purification.

Step 2:

To a solution of crude diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (0.26 mmol) from the previous step in a mixture of MeOH (8.5 mL) and water (1.5 mL) was added powdered lithium hydroxide monohydrate (86 mg, 2.08 mmol). The resulting mixture was stirred for 16 h before the organic volatile was removed under reduced pressure. The residue was diluted with additional water (11 mL) and extracted with EtOAc (12 mL). The organic layer was discarded. The aqueous phase was acidified to pH˜2.5 with 1N aq. HCl solution and extracted with EtOAc (3×12 mL). The combined organic layer was dried (Na₂SO₄), filtered and concentrated to provide the title compound (45.5 mg) as a light brown solid.

¹H NMR (CD₃OD, 300 MHz): δ 8.94 (s, 1H), 6.08 (d, J=7.52 Hz, 1H), 5.05 (d, J=7.52 Hz, 1H), 4.65 (s, 1H), 4.29 (t, J=2.40 Hz, 1H), 4.06 (dd, J=10.7, 2.5 Hz, 1H), 3.93 (dd, J=10.64, 2.50 Hz, 1H), 3.12 (s, 1H); LC/MS [M+H]=428.

Example 27 Synthesis of 2-(((2R,3S,4R,5R)-3-((1H-pyrazol-3-yl)ethynyl)-5-(6-amino-2-chloro-9H-purin-9-yl)-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

Step 1:

To a mixture of 3-iodo-1H-pyrazole (407 mg, 2.1 mmol), PdCl₂(PPh₃)₂ (82 mg, 0.12 mmol), CuI (22 mg, 0.12 mmol), and Et₃N (10 mL) in THF (10 mL) under argon atmosphere was added diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-N,N′-(bis-(tert-butoxycarbonyl)-amino)-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (1 g, 1.2 mmol). The resulting mixture was stirred at 60° C. overnight before it was allowed to cool to room temperature and the organic volatile was removed under reduced pressure. The resulting crude residue was purified by flash silica gel column chromatography (60-100% EtOAc in hexanes) to provide diethyl 2-(((2R,3R,4R,5R)-3-((1H-pyrazol-3-yl)ethynyl)-3,4-diacetoxy-5-(6-N,N′-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)tetrahydro-furan-2-yl)methoxy)malonate as a solid.

Step 2:

To a solution of diethyl 2-(((2R,3R,4R,5R)-3-((1H-pyrazol-3-yl)ethynyl)-3,4-diacetoxy-5-(6-N,N′-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)tetrahydro-furan-2-yl)methoxy)malonate (100 mg, 0.12 mmol) in a DCM (3 mL) was added TFA (1 mL). The resulting mixture was stirred at 25° C. for 4 h before it was concentrated to provide crude diethyl 2-(((2R,3R,4R,5R)-3-((1H-pyrazol-3-yl)ethynyl)-3,4-diacetoxy-5-(6-amino-2-chloro-9H-purin-9-yl)tetrahydrofuran-2-yl)methoxy)malonate which was used in the next step without further purification.

Step 3:

To a solution of crude diethyl 2-(((2R,3R,4R,5R)-3-((1H-pyrazol-3-yl)ethynyl)-3,4-diacetoxy-5-(6-amino-2-chloro-9H-purin-9-yl)tetrahydrofuran-2-yl)methoxy)malonate in a mixture of THF (5 mL) and H₂O (2 mL) was added LiOH·H₂O (50 mg, 1.2 mmol). The resulting mixture was stirred at 25° C. for 24 h before it was cooled to 0° C. and acidified to pH 6.5 with 1N aq. HCl. The reaction mixture was concentrated. The crude residue was purified by preparative reversed-phase HPLC and dried by lyophilization to provide the title compound as a white solid.

¹H NMR (CD₃OD, 300 MHz) δ 8.96 (s, 1H), 7.56-7.76 (m, 1H), 6.50-6.57 (m, 1H), 6.12-6.14 (d, J=7.14 Hz, 1H), 5.13-5.15 (d, J=6.78 Hz, 1H), 4.63-4.70 (m, 1H), 4.38 (s, 1H), 3.99-4.13 (m, 2H); LC/MS [M+H]=495.

Examples 28 & 29 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-((1-benzyl-1H-pyrazol-3-yl)ethynyl)-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid & 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-((1-benzyl-1H-pyrazol-5-yl)ethynyl)-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

Step 1:

To a solution of diethyl 2-(((2R,3R,4R,5R)-3-((1H-pyrazol-3-yl)ethynyl)-3,4-diacetoxy-5-(6-N,N′-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)tetrahydro-furan-2-yl)methoxy)malonate (100 mg, 0.12 mmol), in anhydrous DMF (2 mL) under argon atmosphere at 0° C. was added oven dried Cs₂CO₃ (78 mg, 0.24 mmole). The mixture was stirred at room temperature for 20 minutes followed by addition of benzyl bromide (29 ul, 0.24 mmole). The resulting mixture was stirred at room temperature for 2 h before it was diluted with EtOAc (15 mL) and H₂O (5 mL). The organic layer was separated, washed with H₂O (20 mL), brine, dried over Na₂SO₄ and concentrated. The crude residue was purified by flash silica gel column chromatography (0-50% EtOAc in hexanes) to provide diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-3-((1-benzyl-1H-pyrazol-3-yl)ethynyl)-5-(6-N,N′-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)tetrahydrofuran-2-yl)methoxy)-malonate and diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-3-((1-benzyl-1H-pyrazol-5-yl)ethynyl)-5-(6-N,N′-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)tetrahydro-furan-2-yl)methoxy)malonate.

Steps 2-3:

Proceeding as described in Example 27 above but substituting diethyl 2-(((2R,3R,4R,5R)-3-((1H-pyrazol-3-yl)ethynyl)-3,4-diacetoxy-5-(6-N,N′-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)tetrahydrofuran-2-yl)methoxy)malonate with diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-3-((1-benzyl-1H-pyrazol-3-yl)ethynyl)-5-(6-N,N′-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)tetrahydrofuran-2-yl)methoxy)-malonate provided the title compound (Example 28) acid as a white solid.

¹H NMR (CD₃OD, 300 MHz) δ 8.95 (s, 1H), 7.685 (s, 1H), 7.22-7.38 (m, 5H), 6.50 (s, 1H), 6.10-6.13 (d, J=7.05 Hz, 1H), 5.35 (s, 2H), 5.16-5.18 (d, J=7.35 Hz, 1H), 4.68-4.76 (m, 1H), 4.38 (s, 1H), 3.96-4.16 (dd, J=9.84 Hz, J=17 Hz, 2H); LC/MS [M+H]=585.

Steps 4-5:

Proceeding as described in Example 27 above but substituting diethyl 2-(((2R,3R,4R,5R)-3-((1H-pyrazol-3-yl)ethynyl)-3,4-diacetoxy-5-(6-N,N′-(bis-(tert-butoxy-carbonyl)amino)-2-chloro-9H-purin-9-yl)tetrahydrofuran-2-yl)methoxy)malonate with diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-3-((1-benzyl-1H-pyrazol-5-yl)ethynyl)-5-(6-N,N′-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)tetrahydrofuran-2-yl)methoxy)-malonate provided the title compound (Example 29) as a white solid.

¹H NMR (CD₃OD, 300 MHz) δ 8.88 (s, 1H), 7.53 (s, 1H), 7.23-7.35 (m, 5H), 6.59 (s, 1H), 6.10-6.13 (d, J=6.09 Hz, 1H), 5.46 (s, 2H), 5.15-5.17 (d, J=6.9 Hz, 1H), 4.35-4.41 (m, 2H), 3.71-4.01 (dd, J=10.71, J=33, 2H); LC/MS [M+H]=585.

Examples 30 & 31 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(5-chloro-7-(isopropylamino)-3H-imidazo[4,5-b]pyridin-3-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid & 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-(dimethylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

Step 1:

To a solution of diethyl 2-benzyl-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-ethynyltetra-hydrofuran-2-yl)methoxy)malonate (500 mg, 0.91 mmol) in MeCN (6 mL) at 25° C. was added 5,7-dichloro-1H-imidazo[4,5-b]pyridine (223 mg, 1.18 mmol) and followed by N,O-bis(trimethylsilyl)acetamide (BSA) (535 uL, 2.19 mmol). The resulting suspension was heated at 85° C. for 15 min as it became clear. The reaction mixture was allowed to cool to room temperature followed by addition of TMSOTf (262 mg, 1.18 mmol) dropwise. The reaction mixture was then refluxed at 85° C. for 3 h as all of the starting material was consumed. The reaction was quenched with cold saturated aq. NaHCO₃ solution and diluted with EtOAc (15 mL). The organic layer was separated, washed with H₂O (20 mL), brine, dried over Na₂SO₄ and concentrated. The crude residue was purified by flash silica gel column chromatography (0-50% EtOAc in hexanes) to provide diethyl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(5,7-dichloro-3H-imidazo[4,5-b]pyridin-3-yl)-3-ethynyl-tetrahydrofuran-2-yl)methoxy)malonate as a foam.

Step 2:

To a sealed tube containing diethyl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(5,7-dichloro-3H-imidazo[4,5-b]pyridin-3-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (80 mg, 0.12 mmol) in anhydrous DMF (1 mL) was added isopropyl amine (0.5 mL, 5.9 mmol) and Et₃N (1 mL, 7.1 mmol). The reaction mixture was heated at 75° C. for 72 h before it was allowed to cool and diluted with EtOAc (15 mL) and H₂O (5 mL). The organic layer was separated, washed with H₂O (20 mL), brine, dried over Na₂SO₄ and concentrated. The residue was purified by flash silica gel column chromatography (0-50% EtOAc in hexanes) to provide diethyl 2-benzyl-2-(((2R,3S,4R,5R)-5-(5-chloro-7-(isopropylamino)-3H-imidazo-[4,5-b]pyridin-3-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonate and diethyl 2-benzyl-2-(((2R,3S,4R,5R)-5-(5-chloro-7-(dimethylamino)-3H-imidazo[4,5-b]-pyridin-3-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonate as foam.

Step 3:

To a solution of diethyl 2-benzyl-2-(((2R,3S,4R,5R)-5-(5-chloro-7-(isopropylamino)-3H-imidazo[4,5-b]pyridin-3-yl)-3-ethynyl-3,4-dihydroxytetra-hydrofuran-2-yl)methoxy)-malonate (10 mg, 0.016 mmol) in a mixture of THF (3 mL) and H₂O (1 mL) was added LiOH·H₂O (10 mg, 0.24 mmol). The resulting mixture was stirred at 25° C. for 24 h before it was cooled to 0° C. and acidified to pH 6.5 with 1N aq. HCl. The crude residue was purified by preparative reversed-phase HPLC and dried by lyophilization to provide 2-benzyl-2-(((2R,3S,4R,5R)-5-(5-chloro-7-(isopropylamino)-3H-imidazo[4,5-b]pyridin-3-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid as a white solid.

¹H NMR (CD₃OD, 300 MHz) δ 8.25 (s, 1H), 7.25-7.28 (m, 2H), 7.05 (m, 3H), 6.43 (s, 1H), 6.06-6.08 (d, J=7.17 Hz, 1H), 4.95-4.98 (d, J=7.05 Hz, 1H), 4.32 (s, 1H), 4.05-4.11 (m, 2H), 3.89-3.93 (m, 1H), 3.31-3.39 (m, 2H), 2.99 (s, 1H), 1.30-1.33 (m, 6H); LC/MS [M+H]=560.

Step 4:

To a solution of diethyl 2-benzyl-2-(((2R,3S,4R,5R)-5-(5-chloro-7-(dimethyl-amino)-3H-imidazo[4,5-b]pyridin-3-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-malonate (21 mg, 0.035 mmol) in a mixture of THF (3 mL) and H₂O (1 mL) was added LiOH·H₂O (30 mg, 0.71 mmol). The resulting mixture was stirred at 25° C. for 24 h before it was cooled to 0° C. and acidified to pH 6.5 with 1N aq. HCl. The reaction mixture was concentrated. The crude residue was purified by preparative reversed-phase HPLC and dried by lyophilization to provide the title compound as a white solid.

¹H NMR (CD₃OD, 300 MHz) δ 8.68 (s, 1H), 7.21-7.24 (m, 2H), 6.99-7.03 (m, 3H), 6.49 (s, 1H), 6.15-6.17 (d, J=7.08 Hz, 1H), 4.99-5.02 (d, J=7.17 Hz, 1H), 4.35-4.37 (t, J=3.12 Hz, 1H), 4.07-4.08 (m, 2H), 3.36-3.50 (m, 8H), 2.99 (s, 1H); LC/MS [M+H]=546.

Example 32 Synthesis of 2-(((2R,3S,4R,5R)-5-(2-chloro-6-((2-hydroxyethyl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(thiophen-3-ylmethyl)malonic acid

Steps 1-3:

Proceeding as described in Example 15 above but substituting allyl bromide with 3-(bromomethyl)thiophene provided diethyl 2-(thiophen-3-ylmethyl)-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate as a solid.

Step 4:

To a solution of 5,7-dichloro-1H-imidazo[4,5-b]pyridine (238 mg, 1.26 mmol) in MeCN (6 mL) at 25° C. was added N,O-bis(trimethylsilyl)acetamide (BSA) (571 uL, 2.34 mmol). The resulting suspension was heated at 85° C. for 15 min as it became clear. The reaction mixture was allowed to cool to room temperature followed by addition of diethyl 2-(thiophen-3-ylmethyl)-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-ethynyltetrahydrofuran-2-yl)-methoxy)malonate (540 mg, 0.97 mmol) and TMSOTf (228 ul, 1.26 mmol) dropwise. The reaction mixture was then refluxed at 85° C. for 2.5 h as all of the starting material was consumed. The reaction was quenched with cold saturated aq. NaHCO₃ solution and diluted with EtOAc (15 mL). The organic layer was separated, washed with H₂O (20 mL), brine, dried over Na₂SO₄ and concentrated. The crude residue was purified by flash silica gel column chromatography (0-50% EtOAc in hexanes) to provide diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(2,6-dichloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-2-(thiophen-3-ylmethyl)malonate as a foam.

Step 5:

To a solution of diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(2,6-dichloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-2-(thiophen-3-ylmethyl)malonate (100 mg, 0.146 mmol) in 1,4-dioxane (2 mL) was added TEA (20 uL, 0.146 mmol) followed by ethanolamine (13 ul, 0.219 mmole). The resulting mixture was stirred at 25° C. for 2 h before it was diluted with EtOAc (15 mL) and H₂O (5 mL). The organic layer was separated, washed with H₂O (20 mL), brine, dried over Na₂SO₄ and concentrated to provide crude diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(2-chloro-6-((2-hydroxyethyl)amino)-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-2-(thiophen-3-ylmethyl)malonate which was used in the next step without further purification.

Step 6:

To a solution of crude diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(2-chloro-6-((2-hydroxyethyl)amino)-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-2-(thiophen-3-ylmethyl)malonate in a mixture of THF (4 mL) and H₂O (1 mL) was added LiOH·H₂O (80 mg, 1.91 mmol). The resulting mixture was stirred at 25° C. for 24 h before it was cooled to 0° C. and acidified to pH 6.5 with 1N aq. HCl. The reaction mixture was concentrated. The crude residue was purified by preparative reversed-phase HPLC and dried by lyophilization to provide the title compound as a white solid.

¹H NMR (CD₃OD, 300 MHz) δ 8.32 (s, 1H), 7.09-7.16 (m, 2H), 6.97-6.99 (m, 1H), 6.00-6.03 (d, J=7.41 Hz, 1H), 4.99-5.02 (d, J=7.38 Hz, 1H), 4.32-4.34 (t, J=3.03 Hz, 1H), 4.00-4.11 (m, 2H), 3.65-3.79 (m, 4H), 3.40-3.53 (q, J=15.42 Hz, J=5.79 Hz, 2H), 2.98 (s, 1H); LC/MS [M+H]=568.0.

Example 33 Synthesis of 2-(((2R,3S,4R,5R)-5-(2-chloro-6-(isopropylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(thiophen-3-ylmethyl)malonic acid

Proceeding as described in Example 32 above but substituting ethanolamine with i-PrNH₂ provided the title compound as a white solid.

¹H NMR (CD₃OD, 300 MHz) δ 8.28 (s, 1H), 7.08-7.16 (m, 2H), 6.97-6.99 (m, 1H), 5.99-6.02 (d, J=7.38 Hz, 1H), 5.00-5.02 (d, J=7.35 Hz, 1H), 4.31-4.43 (m, 2H), 4.00-4.12 (m, 2H), 3.40-3.53 (q, J=15.63 Hz, J=5.4 Hz, 2H), 2.98 (s, 1H), 1.27-1.32 (m, 6H); LC/MS [M+H]=566.0.

Example 34 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-((3-hydroxypropyl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

Step 1:

To a solution of 2,6-dichloro-9H-purine_(690 mg, 3.65 mmol) in dry CH₃CN (15 mL) was added N,O-bis(trimethylsilyl)acetamide (0.28 mL, 1.12 mmol) via syringe. The mixture was heated to 95° C. under argon atmosphere for 5 minutes and then cooled to ambient. To this mixture was added diethyl 2-benzyl-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-ethynyltetra-hydrofuran-2-yl)methoxy)malonate (2 g, 3.65 mmol) and followed by TMSOTf (0.09 mL, 0.494 mmol). The resulting mixture was heated at 95° C. for 2.5 h before it was cooled to ambient temperature and diluted with water (60 mL) and EtOAc (60 mL). The organic phase was washed successively with equal volumes of saturated NaHCO₃ solution and brine. The aqueous phase was further extracted with EtOAc (2×30 mL). The combined organic phase was dried (MgSO₄), filtered and concentrated. The crude residue was purified by flash silica gel column chromatography (5-60% EtOAc in hexane) to provide diethyl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(2,6-dichloro-9H-purin-9-yl)tetrahydrofuran-2-yl)-methoxy)malonate (1.61 g) as an off-white solid.

Step 2:

To a solution of diethyl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(2,6-dichloro-9H-purin-9-yl)tetrahydrofuran-2-yl)methoxy)malonate (102 mg, 0.15 mmol) in dry dioxane (1 mL) was added triethylamine (0.02 mL, 0.15 mmol) and 3-aminopropanol (16 mg, 0.212 mmol). The resulting mixture was stirred for 1.5 h before it was diluted with water (15 mL) and DCM (15 mL). and the organic phase was collected. The organic layer was washed with brine (15 mL). The aqueous phase were further extracted with EtOAc (2×10 mL). The combined organic layer was dried over MgSO₄, filtered and concentrated to provide crude diethyl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(2-chloro-6-((3-hydroxypropyl)amino)-9H-purin-9-yl)tetrahydrofuran-2-yl)methoxy)malonate as a clear viscous oil.

Step 3:

To a solution of crude diethyl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(2-chloro-6-((3-hydroxypropyl)amino)-9H-purin-9-yl)tetrahydrofuran-2-yl)methoxy)malonate (0.15 mmol) in H₂O (0.2 mL), MeOH (1 mL) and THF (0.28 mL) was added powdered LiOH mono-hydrate (43 mg, 1.05 mmol)). The mixture was stirred for 4 h and then sonicated for 30 minutes. Additional LiOH mono-hydrate (7 mg) was added and sonication continued for 1 h before the organic volatile was removed under reduced pressure and the residue was diluted with water (10 mL) and EtOAc (10 mL). The mixture was cooled at 0° C. and acidified to pH˜3 with 1N aq. HCl. The organic phase was collected and the aqueous phase was further extracted with EtOAc (2×10 mL). The combined EtOAc phases were dried over MgSO₄, filtered and concentrated. The crude residue was purified by preparative reversed-phase HPLC to provide the title compound as a off-white solid.

¹H NMR (CD₃OD, 300 MHz) δ 8.19 (bs, 1H), 7.21-7.3 (m, 2H), 7.00-7.10 (m, 3H), 6.00 (d, J=7.36 Hz, 1H), 4.98 (d, J=7.36 Hz, 1H), 4.33 (t, J=3.18 Hz, 1H), 4.02-4.15 (m, 2H), 3.68 (t, J=6.18 Hz, 2H), 3.59-3.72 (m, 2H), 3.47 (d, J=14.95 Hz, 1H), 3.38 (d, J=14.95 Hz, 1H), 2.99 (s, 1H), 1.84-1.95 (m, 2H); LC/MS [M+H]=576.0.

Example 35 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-(((R)-2-hydroxypropyl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

Proceeding as described in Example 34 above but substituting propanolamine with (R)-1-aminopropan-2-ol and followed by ester hydrolysis with LiOH provided the title compound as a white solid.

¹H NMR (CD₃OD, 300 MHz) δ 8.19 (bs, 1H), 7.22-7.30 (m, 2H), 7.02-7.10 (m, 3H), 6.01 (d, J=7.38 Hz, 1H), 4.98 (d, J=7.38 Hz, 1H), 4.33 (t, J=3.17 Hz, 1H), 3.99-4.13 (m, 3H), 3.58-3.69 (m, 1H), 3.43 (qt, J=14.64 Hz, 2H), 3.41-3.55 (m, 1H), 2.99 (s, 1H), 1.24 (d, J=6.30 Hz, 3H); LC/MS [M+H]=576.0.

Example 36 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-(((S)-2-hydroxypropyl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

Proceeding as described in Example 34 above but substituting propanolamine with (S)-1-aminopropan-2-ol and followed by ester hydrolysis with LiOH provided the title compound as a white solid.

¹H NMR (CD₃OD, 300 MHz) δ 8.19 (bs, 1H), 7.23-7.29 (m, 2H), 7.03-7.10 (m, 3H), 6.00 (d, J=7.35 Hz, 1H), 4.96 (d, J=7.35 Hz, 1H), 4.32 (t, J=3.30 Hz, 1H), 3.98-4.13 (m, 3H), 3.59-3.68 (m, 1H), 3.35-3.55 (m, 3H), 2.99 (s, 1H), 1.25 (d, J=6.30 Hz, 3H); LC/MS [M+H]=576.0.

Example 37 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(6-(bis(2-hydroxyethyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

Proceeding as described in Example 34 above but substituting propanolamine with diethanolamine and followed by ester hydrolysis with LiOH provided the title compound as a white solid.

¹H NMR (CD₃OD, 300 MHz) δ 8.16 (s, 1H), 7.22-7.29 (m, 2H), 6.99-7.09 (m, 3H), 6.02 (d, J=7.33 Hz, 1H), 4.97 (d, J=7.33 Hz, 1H), 4.00-4.37 (m, 2H), 4.29-4.34 (m, 2H), 4.03-4.13 (m, 3H), 3.84-3.91 (m, 4H), 3.46 (d, J=14.92 Hz, 1H), 3.37 (d, J=14.92 Hz, 1H), 2.98 (s, 1H); LC/MS [M+H]=606.0.

Example 38 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-((2-methoxyethyl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

Proceeding as described in Example 34 above but substituting propanolamine with 2-methoxyethylamine and followed by ester hydrolysis with LiOH provided the title compound as a white solid.

¹H NMR (CD₃OD, 300 MHz) δ 8.17 (bs, 1H), 7.22-7.30 (m, 2H), 7.01-7.09 (m, 3H), 6.01 (d, J=7.33 Hz, 1H), 4.98 (d, J=7.33 Hz, 1H), 4.33 (t, J=3.20 Hz, 1H), 4.03-4.13 (m, 2H), 3.69-3.79 (m, 2H), 3.62 (t, J=5.13 Hz, 2H), 3.47 (d, J=14.89 Hz, 1H), 3.40 (s, 3H), 3.38 (d, J=14.89 Hz, 1H), 2.99 (s, 1H); LC/MS [M+H]=576.0.

Example 39 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-((2-methoxyethyl)-(methyl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

Proceeding as described in Example 34 above but substituting propanolamine with (2-methoxyethyl)methylamine and followed by ester hydrolysis with LiOH provided the title compound as a white solid.

¹H NMR (CD₃OD, 300 MHz) δ 8.18 (bs, 1H), 7.22-7.29 (m, 2H), 6.99-7.09 (m, 3H), 6.02 (d, J=7.21 Hz, 1H), 4.98 (d, J=7.21 Hz, 1H), 4.32 (t, J=3.41 Hz, 1H), 4.03-4.14 (m, 2H), 3.68 (t, J=5.42 Hz, 2H), 3.34-3.49 (m, 7H), 3.36 (s, 3H), 2.99 (s, 1H); LC/MS [M+H]=590.0.

Example 40 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-(((1-hydroxycyclobutyl)-methyl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

Proceeding as described in Example 34 above but substituting propanolamine with 1-(aminomethyl)cyclobutanol and followed by ester hydrolysis with LiOH provided the title compound as a white solid.

¹H NMR (CD₃OD, 300 MHz) δ 8.18 (bs, 1H), 7.23-7.29 (m, 2H), 7.01-7.09 (m, 3H), 6.01 (d, J=7.36 Hz, 1H), 4.98 (d, J=7.36 Hz, 1H), 4.32 (t, J=3.21 Hz, 1H), 4.03-4.11 (m, 2H), 3.73-3.79 (m, 2H), 3.36-3.50 (m, 2H), 2.99 (s, 1H), 2.03-2.21 (m, 4H), 1.59-1.85 (m, 2H); LC/MS [M+H]=602.0.

Example 41 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-(3-hydroxyazetidin-1-yl)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

Proceeding as described in Example 34 above but substituting propanolamine with azetidin-3-ol and followed by ester hydrolysis with LiOH provided the title compound as a white solid.

¹H NMR (CD₃OD, 300 MHz) δ 8.29 (bs, 1H), 7.21-7.29 (m, 2H), 6.99-7.11 (m, 3H), 6.01 (d, J=7.33 Hz, 1H), 5.01 (d, J=7.33 Hz, 1H), 4.57-4.82 (m, 3H), 4.33 (t, J=3.39 Hz, 1H), 4.14-4.27 (m, 2H), 4.07 (qd, J=4.04, 2.92 Hz, 2H), 3.30-3.50 (m, 2H), 2.98 (s, 1H); LC/MS [M+H]=574.0.

Example 42 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-(2-(hydroxymethyl)azetidin-1-yl)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

Proceeding as described in Example 34 above but substituting propanolamine with azetidin-2-ylmethanol and followed by ester hydrolysis with LiOH provided the title compound as a white solid.

¹H NMR (CD₃OD, 300 MHz) δ 8.17-8.29 (m, 1H), 7.22-7.28 (m, 2H), 7.01-7.12 (m, 3H), 5.98-6.03 (m, 1H), 4.98 (d, J=7.30 Hz, 1H), 4.27-4.45 (m, 3H), 4.00-4.13 (m, 3H), 3.83-3.92 (m, 1H), 3.33-3.50 (m, 3H), 2.99 (s, 0.5H), 2.97 (s, 0.5H), 2.49-2.63 (m, 1H), 2.31-2.64 (m, 1H); LC/MS [M+H]=588.0.

Example 43 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-((1-(hydroxymethyl)-cyclopropyl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

Proceeding as described in Example 34 above but substituting propanolamine with (1-aminocyclopropyl)methanol and followed by ester hydrolysis with LiOH provided the title compound as a white solid.

¹H NMR (CD₃OD, 300 MHz) δ 8.18 (s, 1H), 7.22-7.32 (m, 2H), 7.02-7.11 (m, 3H), 6.01 (d, J=7.36 Hz, 1H), 4.96 (d, J=7.36 Hz, 1H), 4.32 (t, J=3.24 Hz, 1H), 4.02-4.14 (m, 2H), 3.76 (bs, 2H), 3.46 (d, J=15.04 Hz, 1H), 3.38 (d, J=15.04 Hz, 1H), 2.99 (s, 1H), 0.88-1.03 (m, 4H); LC/MS [M+H]=588.0.

Example 44 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-(((1-hydroxycyclopropyl)-methyl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

Proceeding as described in Example 34 above but substituting propanolamine with 1-(aminomethyl)cyclopropanol and followed by ester hydrolysis with LiOH provided the title compound as a white solid.

¹H NMR (CD₃OD, 300 MHz) δ 8.18 (s, 1H), 7.08-7.25 (m, 5H), 5.98-6.02 (d, J=7 Hz, 1H), 4.93-4.97 (m, 2H), 4.30 (bs, 1H), 3.98-4.10 (m, 2H), 3.71 (bs, 2H), 3.39-3.51 (m, 2H), 3.00-3.13 (s 1H), 0.71-0.80 (m, 4H); LC/MS [M+H]=588.2.

Example 45 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-((cyclobutylmethyl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

Proceeding as described in Example 34 above but substituting propanolamine with cyclobutylmethanamine and followed by ester hydrolysis with LiOH provided the title compound as a white solid.

¹H NMR (CD₃OD, 300 MHz) δ 8.19 (s, 1H), 7.24-7.27 (m, 2H), 7.05-7.07 (m, 3H), 5.98-6.01 (d, J 8 Hz, 1H), 4.93-4.95 (d, J 7 Hz, 1 Hz), 4.31-4.33 (bs, 1H), 4.01-4.10 (m, 2H), 3.58 (s, 2H), 3.39-3.48 (m, 2H), 3.00 (s, 1H), 2.66-2.71 (m, 1H), 2.12-2.15 (m, 2H) 1.84-1.97 (m, 4H); LC/MS [M+H]=586.2.

Example 46 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-(3-(hydroxymethyl)azetidin-1-yl)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

Proceeding as described in Example 34 above but substituting propanolamine with azetidin-3-ylmethanol and followed by ester hydrolysis with LiOH provided the title compound as a white solid.

¹H NMR (CD₃OD, 300 MHz) δ 8.09 (s, 1H), 7.05-7.25 (m, 5H), 6.00-6.02 (d, J 7 Hz, 1H), 4.93-4.97 (m, 1H), 4.33 (bs, 1H), 3.96-4.11 (m, 2H), 3.78 (bs, 2H), 3.36-3.40 (m, 6H), 2.99 (bs, 2H); LC/MS [M+H]=588.2.

Example 47 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-(3-hydroxy-3-methylazetidin-1-yl)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

Proceeding as described in Example 34 above but substituting propanolamine with 3-methylazetidin-3-ol and followed by ester hydrolysis with LiOH provided the title compound as a white solid.

¹H NMR (CD₃OD, 300 MHz) δ 8.30 (s, 1H), 7.08-7.25 (m, 5H), 6.00-6.03 (d, J 7 Hz, 1H), 4.98-5.01 (m, 1H), 4.33 (bs, 4H), 4.01-4.09 (m, 2H), 3.73 (bs, 1H), 3.35-3.47 (m, 2H), 2.98 (s, 1H), 1.57 (s, 3H); LC/MS [M+H]=588.2.

Example 48 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-((3-hydroxycyclobutyl)-(methyl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

Proceeding as described in Example 34 above but substituting propanolamine with 3-(methylamino)cyclobutanol and followed by ester hydrolysis with LiOH provided the title compound as a white solid.

¹H NMR (CD₃OD, 300 MHz) δ 8.26 (s, 1H), 6.96-7.28 (m, 5H), 6.02-6.04 (d, J 7 Hz, 1H), 5.27 (bs, 1H), 4.98-5.02 (m, 1H), 4.33 (bs, 2H), 3.95-4.15 (m, 3H), 3.36-3.51 (m, 4H), 2.99 (s, 1H), 2.67-2.69 (m, 2H), 2.22-2.25 (m, 2H); LC/MS [M+H]=602.2.

Examples 49 & 50 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-ethoxy-3-oxo-2-(3-(trifluoromethyl)-benzyl)propanoic acid & 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(3-(trifluoromethyl)benzyl)malonic acid

Proceeding as described in Example 8 above but substituting furan with (3-trifluoro-methyl)benzene provided the title compounds both as white solid by preparative reversed-phase HPLC purification. 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydro-furan-2-yl)methoxy)-3-ethoxy-3-oxo-2-(3-(trifluoromethyl)-benzyl)propanoic acid: ¹H NMR (CD₃OD, 300 MHz) δ 8.33 (bs, 1H), 7.51-7.54 (d, J=8 Hz, 2H), 7.38-7.40 (d, J=6 Hz, 1H), 7.21-7.26 (t, J=7 Hz, 1H), 6.00-6.04 (m, 1H), 4.98-5.02 (dt, J=4.7, 52 Hz, 1H), 4.36 (bs, 1H), 4.02-4.22 (m, 4H), 3.45-3.58 (m, 2H), 3.02-3.12 (d, J=29 Hz, 1H), 1.18-1.24 (m, 3H); LC/MS [M+H]=614.2.

2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydro-furan-2-yl)methoxy)-2-(3-(trifluoromethyl)benzyl)malonic acid: ¹H NMR (CD₃OD, 300 MHz) δ 8.30 (s, 1H), 7.52-7.54 (d, J=9 Hz, 2H), 7.37-7.39 (d, J=7 Hz, 1H), 7.23-7.25 (t, J=7 Hz, 1H), 6.01-6.03 (d, J=7 Hz, 1H), 4.97-5.00 (d, J=7 Hz, 1H), 4.37 (bs, 1H), 4.12-4.14 (m, 2H), 3.44-3.57 (m, 2H), 3.01 (s, 1H); LC/MS [M+H]=586.2.

Example 51 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(3-chlorobenzyl)malonic acid

Proceeding as described in Example 8 above but substituting furan with 3-chloro-benzene provided the title compound as a white solid by preparative reversed-phase HPLC purification.

¹H NMR (CD₃OD, 300 MHz) δ 8.42 (s, 1H), 7.27 (bs, 1H), 7.14-7.15 (d, J=6 Hz, 1H), 7.02-7.06 (m, 2H), 6.02-6.05 (d, J=8 Hz, 1H), 5.03-5.06 (d, J=7 Hz, 1H), 4.35-4.39 (m, 2H), 3.39-3.49 (m, 2H), 3.01 (s, 1H), 2.48-2.54 (t, J 8 Hz, 1H) 2.22-2.32 (m, 1H); LC/MS [M+H]=552.1.

Example 52 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(3-methoxybenzyl)malonic acid

Proceeding as described in Example 8 above but substituting furan with 3-methoxy-benzene provided the title compound as a white solid by preparative reversed-phase HPLC purification.

¹H NMR (CD₃OD, 300 MHz) δ 8.40 (s, 1H), 6.96-7.02 (t, J 8 Hz, 1H), 6.82 (bs, 2H), 6.59-6.62 (m, 1H), 6.02-6.04 (d, J=7 Hz, 1H), 5.01-5.04 (d, J=8 Hz, 1H), 4.35-4.39 (m, 2H), 3.54 (s, 3H), 3.45-3.50 (m, 1H), 2.97 (s, 1H), 2.48-2.54 (t, J 8 Hz, 1H) 2.22-2.32 (m, 1H); LC/MS [M+H]=548.1.

Example 53 Synthesis of 2-([1,1′-biphenyl]-4-ylmethyl)-2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

Proceeding as described in Example 8 above but substituting furan with 3-biphenyl provided the title compound as a white solid by preparative reversed-phase HPLC purification.

¹H NMR (CD₃OD, 300 MHz) δ 8.23 (s, 1H), 7.28-7.43 (m, 9H), 5.99-6.02 (d, J=7 Hz, 1H), 4.96-4.98 (d, J=7 Hz, 1H), 4.35 (s, 1H), 4.08-4.15 (m, 2H), 3.41-3.57 (m, 2H), 3.04 (s, 1H): LC/MS [M+H]=594.2.

Example 54 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-((2′-carboxy-[1,1′-biphenyl]-4-yl)methyl)malonic acid

Proceeding as described in Example 8 above but substituting furan with 3-methyl [1,1′-biphenyl]-2-carboxylate provided the title compound as a white solid by preparative reversed-phase HPLC purification.

¹H NMR (CD₃OD, 300 MHz) δ 8.27 (s, 1H), 7.71-7.73 (d, J 7 Hz, 1H), 7.29-7.48 (m, 4H), 7.14-7.16 (d, J=8 Hz, 1H), 7.08-7.10 (d, J=8 Hz, 2H), 5.99-6.01 (d, J=8 Hz, 1H), 4.88-4.91 (m, 1H), 4.30 (bs, 1H), 4.03-4.12 (m, 2H), 3.39-3.57 (m, 2H), 2.99 (s, 1H); LC/MS [M+H]=638.2.

Example 55 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

Diethyl 2-(((2R,3R,4S,5R)-5-(N₆,N₆-bis-Boc-2-chloro-9H-purin-9-yl)-3-((tert-butoxycarbonyl)oxy)-4-fluorotetrahydrofuran-2-yl)methoxy)malonate (100 mg, 0.13 mmol) was dissolved in EtOAc (2 mL). The solution was purged three times with Argon gas and followed by careful addition of palladium on carbon (20 mg, 10 wt %). The resulting slurry was purged three times with Argon gas and then placed under H₂ (1 atm in a balloon). The reaction was held for 70 h at ambient temperature. The suspension was filtered through diatomaceous earth, washed with EtOAc (3×2 mL). The filtrate was concentrated to an oil which was then dissolved in DCM (1 mL) and followed by addition of TFA (100 μL). The resulting solution was held overnight before it was concentrated. The pale yellow oil residue was dissolved in THF (1 mL) and cooled at 0° C. To this reaction mixture was added 4M NaOH (100 μL) and the reaction was allowed to warm to ambient temperature over 14 h before it was concentrated. The crude residue was purified by preparative reversed-phase HPLC to provide the title compound as a white solid.

¹H NMR (CD₃OD, 300 MHz) δ 8.90 (s, 1H), 6.09-6.11 (d, J=7 Hz, 1H), 4.69-4.72 (d, J=8 Hz, 1H), 4.64 (bs, 1H), 4.19 (s, 1H), 3.83 (bs, 3H), 1.88-1.95 (m, 3H), 1.06-1.11 (t, J 7 Hz, 3H); LC/MS [M+H]=432.2.

Example 56 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-benzylmalonic acid

Step 1:

A mixture of diethyl 2-benzyl-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-ethynyltetrahydro-furan-2-yl)methoxy)malonate (1.0 mmol, 549 mg) and palladium on carbon (100 mg, 10 wt %) in EtOH (5 mL) and EtOAc (5 mL) under an atmosphere of H₂ was stirred for 24 h before it was filtered through diatomaceous earth, rinsed with EtOAc (3×5 mL). The filtrate was concentrated and purified via flash silica gel column chromatography to provide diethyl 2-benzyl-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-ethyltetrahydrofuran-2-yl)methoxy)malonate.

Steps 2-3:

Proceeding as described in Example 7 above but substituting diethyl 2-(pyridin-4-ylmethyl)-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate with diethyl 2-benzyl-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-ethyltetrahydrofuran-2-yl)methoxy)-malonate and followed by ester hydrolysis provided the title compound as a white solid via preparative reversed-phase HPLC purification.

¹H NMR (CD₃OD, 300 MHz) δ 8.46 (s, 1H), 7.18-7.20 (m, 2H), 7.04-7.09 (m, 3H), 6.01-6.04 (d, J 8 Hz, 1H), 4.63-4.66 (d, J=8 Hz, 1H), 4.21 (bs, 1H), 3.76-3.96 (m, 2H), 3.39-3.52 (m, 2H), 1.76-1.83 (m, 2H), 0.98-1.03 (t, J=7 Hz, 3H); LC/MS [M+H]=522.2

Example 57 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3,4-dihydroxy-3-vinyltetrahydrofuran-2-yl)methoxy)-2-benzylmalonic acid

Step 1:

A mixture of diethyl 2-benzyl-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-ethynyltetra-hydrofuran-2-yl)methoxy)malonate (525 mg, 0.96 mmol) and Lindlar catalyst (105 mg, 5 wt %) in EtOH (5 mL) and EtOAc (5 mL) under an atmosphere of H₂ was stirred for 24 h before it was filtered through diatomaceous earth, rinsed with EtOAc (3×5 mL). The filtrate was concentrated and purified via flash silica gel column chromatography to provide diethyl 2-benzyl-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-vinyltetrahydrofuran-2-yl)methoxy)malonate.

Steps 2-3:

Proceeding as described in Example 7 above but substituting diethyl 2-(pyridin-4-ylmethyl)-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate with diethyl 2-benzyl-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-vinyltetrahydrofuran-2-yl)methoxy)-malonate and followed by ester hydrolysis provided the title compound as a white solid via preparative reversed-phase HPLC purification.

¹H NMR (CD₃OD, 300 MHz) δ 8.44 (s, 1H), 7.21-7.22 (m, 2H), 7.06-7.11 (m, 3H), 6.14-6.23 (m, 1H), 6.08-6.10 (d, J=8 Hz, 1H), 5.55-5.61 (m, 1H), 5.25-5.29 (m, 1H), 4.81 (s, 1H), 4.14 (bs, 1H), 3.91-3.94 (m, 1H), 3.62-3.65 (d, J 9 Hz, 1H), 3.50-3.55 (d, J 15 Hz, 1H), 3.39 (s, 1H); LC/MS [M+H]=520.1.

Example 58 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(5-chloro-3H-imidazo[4,5-b]pyridin-3-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

Step 1:

To a solution of an anomeric mixture of diethyl 2-benzyl-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (175 mg, 0.319 mmol) in dry dichloroethane (3.5 mL) was added 5-chloro-3H-imidazo[4,5-b]pyridine (65 mg, 0.422 mmol) and followed by addition of N,O-bis(trimethylsilyl)acetamide (BSA) (0.28 mL, 1.12 mmol) via syringe. The mixture was heated at 95° C. under argon atmosphere for 1 h before it was cooled to ambient temperature and followed by addition of TMSOTf (0.09 mL, 0.494 mmol) via syringe. The resulting mixture was heated at 95° C. for 5 h before it was allowed to cool and diluted with water (30 mL) and extracted with EtOAc (30 mL). The organic phase was washed successively with equal volumes of saturated NaHCO₃ solution and brine. The aqueous phases was further extracted with EtOAc (2×30 mL). The combined organic phase was dried (MgSO₄), filtered and concentrated. The crude residue was purification by preparative TLC (55% EtOAc in hexanes) to provide less polar diethyl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(5-chloro-3H-imidazo[4,5-b]pyridin-3-yl)-3-((trimethyl-silyl)ethynyl)tetrahydrofuran-2-yl)methoxy)malonate (44 mg) as a viscous oil and the desired diethyl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(5-chloro-3H-imidazo[4,5-b]pyridin-3-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (22 mg) as a viscous oil.

Step 2:

To a solution of diethyl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(5-chloro-3H-imidazo[4,5-b]pyridin-3-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (22 mg, 0.034 mmol) in THF (0.6 mL) was added a solution of 1N aq. LiOH (0.24 mL). Additional 1N aq. LiOH (0.58 mL) was applied over a period of 2 days with a combination of periodically sonication and stirring. The reaction mixture was concentrated and diluted with water (10 mL) and EtOAc (10 mL). The reaction mixture was cooled at 0° C. and acidified to pH˜3 with 1N aq. HCl. The layers were separated and the aq. layer was further extracted with EtOAc (2×10 mL). The combined organic layer was dried over MgSO₄, filtered and concentrated. The crude residue was purified by preparative reversed-phase HPLC to provide the title compound as a off-white solid.

¹H NMR (CD₃OD, 300 MHz): δ 8.63 (bs, 1H), 8.01 (d, J=8.14 Hz, 1H), 7.34 (d, J=8.14 Hz, 1H), 7.29-7.23 (m, 2H), 7.07-6.99 (m, 3H), 6.21 (d, J=7.33 Hz, 1H), 5.04 (d, J=7.33 Hz, 1H), 4.34 (t, J=3.02 Hz, 1H), 4.14-4.03 (m, 2H), 3.48 (d, J=12.53 Hz, 1H), 3.37 (d, J=12.53 Hz, 1H), 2.99 (s, 1H); LC/MS [M+H]=502.0.

Example 59 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(6-(benzylamino)-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

Step 1:

A suspension of sodium hydride (60%, mineral dispersion; 1.91 g, 47.7 mmoL) in anhydrous THF (150 mL) was cooled to 0° C. and treated with a second solution of (3aR,5R,6R,6aR)-5-(((tert-butyldimethylsilyl)oxy)methyl)-6-ethynyl-2,2-dimethyltetrahydro-furo[2,3-d][1,3]dioxol-6-ol (10 g, 30.4 mmoL) in THF (50 mL) over 15 minutes. After stirring 15 mins at 0° C., the mixture was warmed to room temperature and stirred for an additional 1.5 h. The mixture was then cooled back to 0° C. and treated with MOMCl (6.81 mL, 80.7 mmoL, 2.6 eq) was added dropwise. Once the addition was complete, the cooling bath was removed and stirring was continued for 2 h at room temperature. The reaction was quenched by the slow addition of saturated aqueous ammonium chloride (50 mL), washed with water and extracted with ethyl acetate (100 mL). The organic phase was dried over sodium sulfate, filtered, and concentrated. The crude product was purified via silica gel chromatography (30% ethyl acetate in hexanes) to afford tert-butyl-(((3aR,5R,6R,6aR)-6-ethynyl-6-(methoxy-methoxy)-2,2-dimethyltetrahydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)dimethylsilane (9.95 g, 88% yield) as a white solid.

Step 2:

A solution of the above alcohol (9.8 g, 26.3 mmoL) in anhydrous THF (100 mL) was cooled to 0° C. and treated with 1N solution of tetrabutylammonium fluoride in THF (37 mL, 36.8 mmoL, 1.4 eq) over 15 minutes. After the addition is complete, the reaction was warmed to room temperature and stirred for 3 h. When the reaction was complete (3 h), the volatiles were concentrated affording a viscous residual oil which was dissolved in dichloromethane (5 mL), loaded directly onto a silica gel column (˜300 cc) and purified via silica gel chromatography, eluting with hexanes to 50% Ethyl acetate in hexanes to afford ((3aR,5R,6R,6aR)-6-ethynyl-6-(methoxymethoxy)-2,2-dimethyltetrahydrofuro[2,3-d][1,3]-dioxol-5-yl)methanol (6.18 g, 91% yield) as a white solid.

Step 3:

A solution of the above alcohol (175 mg, 0.678 mmoL) in anhydrous benzene (8 mL) and 1-ethyl 3-(prop-1-en-1-yl) 2-diazomalonate (188 mg, 0.949 mmoL) was treated with rhodium(II) acetate (5.8 mg, 0.013 mmoL, 0.02 eq) and warmed to 60-65° C. for 2 h. Once complete, the solution is concentrated, dissolved in dichloromethane (1.5 mL) and loaded directly onto a silica gel column (˜100 cc) and purified via silica gel chromatography, eluting with (0-50% ethyl acetate in hexanes) to afford 1-ethyl 3-prop-1-en-1-yl 2-(((3aR,5R,6R,6aR)-6-ethynyl-6-(methoxymethoxy)-2,2-dimethyltetrahydrofuro[2,3-d][1,3]-dioxol-5-yl)methoxy)malonate (252 mg, 87%) (mixture of isomers) as a pale-yellow oil.

Step 4:

While under nitrogen, a solution of malonate from the previous step (250 mg, 0.583 mmol) and benzyl bromide (0.42 mL, 3.5 mmol, 6 eq) in anhydrous DMF (8 mL) was treated with and cesium carbonate (760 mg, 2.33 mmol) and stirred at room temperature for 4 h. Once complete, the reaction was filtered through a celite pad, washed with water and extracted with ethyl acetate. The combined organic layers were dried over sodium sulfate, filtered, and concentrated. The residual oil was dissolved in dichloromethane (2 mL), loaded onto a silica gel column (˜100 cc) eluting with 30% ethyl acetate in hexanes to afford 1-ethyl 3-prop-1-en-1-yl 2-benzyl-2-(((3aR,5R,6R,6aR)-6-ethynyl-6-(methoxymethoxy)-2,2-dimethyltetrahydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)malonate (261 mg, 86%) (mixture of isomers) as a pale yellow oil.

Step 5:

While under nitrogen, a water cooled (14-17° C.) solution of the acetonide from the last step (500 mg, 0.964 mmoL) in acetic acid (3.9 mL) was treated with acetic anhydride (0.965 mL, 10.3 mmoL, 10.7 eq) and concentrated sulfuric acid (410 uL, 0.326 mmoL, 0.34 eq). The resulting solution was stirred for 4 h, diluted with water and extracted with ethyl acetate. The combined organic solution washed with sodium bicarbonate (aqueous, saturated; 100 mL), dried (Na₂SO₄), filtered, and concentrated in vacuo. The residual oil was dissolved in dichloromethane (2 mL), and purified on a Biotage flash chromatography system, eluted with hexanes to 50% ethyl acetate in hexanes. A diastereomeric mixture of 1-ethyl 3-prop-1-en-1-yl 2-benzyl-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-ethynyltetrahydrofuran-2-yl)methoxy)-malonate (420 mg, 8%) (separable anomers via silica gel chromatography, 40 G silica gel column) was isolated as a clear oil.

Step 6:

A suspension of 2,6-dichloroadenine (143 mg, 0.76 mmol, 1.01 eq) and N,O-bis(trimethylsilyl)acetamide (0.24 mL, 0.97 mmol, 1.29 eq) in anhydrous acetonitrile (5 mL) was treated with a second solution of 1-ethyl 3-((E)-prop-1-en-1-yl) 2-benzyl-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-ethynyltetrahydrofuran-2-yl)-methoxy)malonate (143 mg, 0.75 mmol) in anhydrous acetonitrile (15 mL), followed by dropwise addition of trimethylsilyl trifluoromethanesulfonate (0.18 mL, 1.0 mmol, 1.33 eq). After the addition was complete, the reaction was warmed to 50° C. for 18 h, then cooled to room temperature. (Reaction begins a pale-yellow color and after 4 h turns to a transparent amber). Once complete, saturated aqueous sodium bicarbonate was added, and the mixture was stirred for 10 minutes. The crude product was then extracted with ethyl acetate (3×30 mL) and the combined organic layer is dried (Na₂SO₄), filtered, and concentrated. The residue was dissolved in dichloromethane and purified on a Biotage flash chromatography system, eluted with hexanes to 50% ethyl acetate in hexanes to give 1-ethyl 3-prop-1-en-1-yl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(2,6-dichloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (as a mixture of isomers) as a white solid (400 mg, 77% yield).

Step 7:

A solution of 1-ethyl 3-prop-1-en-1-yl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(2,6-dichloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-malonate (80 mg, 0.116 mmoL) in anhydrous dioxane (2 mL) was cooled to 0° C. was treated with DIPEA (30 μL, 0.174 mmoL, 1.5 eq) and benzylamine (13 μL, 0.116 mmoL, 1 eq). Once the addition was complete, the solution was warmed to room temperature with continued stirring overnight (18H). The mixture was diluted with ethyl acetate (50 mL) and washed with water (20 mL). The organic layer was dried (Na₂SO₄), filtered, and concentrated. The crude product was purified via Biotage flash chromatography, eluting with 50% ethyl acetate in hexanes to give 1-ethyl 3-prop-1-en-1-yl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-(benzylamino)-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (as a mixture of isomers, ˜1:1) as a white solid (75 mg, 85% yield).

Step 8:

A solution of 1-ethyl 3-prop-1-en-1-yl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-(benzylamino)-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate from the last step (70 mg, 0.092 mmoL) in THF (1 mL) was treated with a LiOH solution (31 mg, 1.35 mmoL, 15 eq; in 1 mL water) and stirred overnight. The resulting solution was acidified with 2N HCl to pH 3 and the resulting suspension was stirred for 10 min., then filtered, washed with cold water and dried. The title compound was isolated as a white solid (50 mg, 89% yield).

¹H NMR (400 MHz, CDCl₃/CD₃OD=5:1) δ 7.98 (s. 1H), 7.25-6.84 (m, 10H), 5.85 (d, J=6.4 Hz, 1H), 4.63 (s, 2H), 4.54 (d, J=6.4 Hz, 1H), 4.17 (t, J=3.2 Hz, 1H), 3.88 (qd, J=10.3, 3.3 Hz, 2H), 3.36-3.16 (m, 2H), 2.49 (s, 1H). HPLC: 9.97 min, 97.0%. ESI-MS (m/z): [M]⁺ calcd for C₂₉H₂₆ClN₅O₈, 608.15; found 608.1.

Example 60 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-((tetrahydro-2H-pyran-4-yl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except tetrahydro-2H-pyran-4-amine was used in place of benzylamine in step 7.

¹H NMR (400 MHz, CDCl₃/CD₃OD=5:1) δ 8.09 (s, 1H), 7.18-7.12 (m, 2H), 7.01 (dd, J=12.1, 7.2 Hz, 3H), 5.90 (d, J=6.3 Hz, 1H), 4.57 (d, J=6.3 Hz, 1H), 4.25 (t, J=3.1 Hz, 2H), 4.00-3.89 (m, 4H), 3.51 (td, J=11.6, 2.2 Hz, 2H), 3.42-3.330 (m, 2H), 2.52 (s, 1H), 1.94 (d, J=13.0 Hz, 2H), 1.57 (td, J=11.2, 3.5 Hz, 2H). ESI-MS (m/z): [M]⁺ calcd for C₂₇H₂₈ClN₅O₉, 602.16; found 602.5.

Example 61 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-((2-(diethylamino)ethyl)-amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except N₁,N₁-diethylethane-1,2-diamine was used in place of benzylamine in step 7.

¹H NMR (400 MHz, DMSO-66): 9.01 (s, 1H), 8.75 (s, 1H), 8.49 (s, 1H), 7.23-7.03 (m, 5H), 6.16 (s, 1H), 5.96 (d, J=7.0 Hz, 1H), 5.84 (d, J=6.9 Hz, 1H), 4.59 (t, J=7.1 Hz, 1H), 4.13 (dd, J=6.7, 2.7 Hz, 1H), 3.83-3.55 (m, 4H), 3.53 (s, 1H), 3.30-3.15 (m, 6H), 3.06-2.97 (m, 2H), 1.26-1.12 (m, 6H). ESI-MS (m/z): [M]⁺ calcd for C₂₈H₃₃ClN₆O₈, 617.20; found 617.5.

Example 62 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-(((R)-1-phenylethyl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except (R)-1-phenylethan-1-amine was used in place of benzylamine in step 7.

¹H NMR (400 MHz, CDCl₃/CD₃OD=5:1) δ 8.25 (s, 1H), 7.44-7.27 (m, 4H), 7.23-6.94 (m, 6H), 5.91 (dd, J=6.2, 1.7 Hz, 1H), 5.46 (d, J=8.0 Hz, 1H), 4.58 (d, J=6.2 Hz, 1H), 4.25 (t, J=2.4 Hz, 1H), 3.98-3.83 (m, 2H), 3.32 (dd, J=6.3, 1.7 Hz, 2H), 2.48 (d, J=1.7 Hz, 1H), 1.59 (dd, J=6.9, 1.7 Hz, 3H). ESI-MS (m/z): [M]⁺ calcd for C₃₀H₂₈ClN₅O₈, 622.16; found 622.1.

Example 63 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-(((S)-1-phenylethyl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except (S)-1-phenylethan-1-amine was used in place of benzylamine in step 7.

¹H NMR (400 MHz, CDCl₃/CD₃OD=5:1) δ 8.11 (s, 1H), 7.40-7.28 (m, 4H), 7.23-6.93 (m, 6H), 5.90 (d, J=5.8 Hz, 1H), 5.45 (s, 1H), 4.52 (d, J=5.8 Hz, 1H), 4.35-4.22 (m, 1H), 3.99 (t, J=2.4 Hz, 2H), 3.42-3.25 (m, 2H), 2.50 (s, 1H), 1.58 (d, J=6.9 Hz, 3H). ESI-MS (m/z): [M]⁺ calcd for C₃₀H₂₈ClN₅O₈, 622.16; found 622.2.

Example 64 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-((tetrahydrofuran-3-yl)-amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except tetrahydrofuran-3-amine was used in place of benzylamine in step 7.

¹H NMR (400 MHz, CDCl₃/CD₃OD=5:1) δ 8.10 (s, 1H), 7.19-6.92 (m, 5H), 5.90 (d, J=6.3 Hz, 1H), 4.72 (s, 1H), 4.58 (d, J=6.3 Hz, 1H) 4.25 (t, J=3.1 Hz, 1H), 3.94 (tp, J=7.0, 4.0, 3.3 Hz, 3H), 3.70 (dt, J=9.4, 3.6 Hz, 2H), 3.43-3.24 (m, 2H), 2.52 (s, 1H), 2.29 (dq, J=13.2, 7.6 Hz, 1H), 1.93 (s, 1H). ESI-MS (m/z): [M]⁺ calcd for C₂₆H₂₆ClN₅O₉, 588.14; found 588.3.

Example 65 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-((S)-3-hydroxypyrrolidin-1-yl)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except (S)-pyrrolidin-3-ol was used in place of benzylamine in step 7.

¹H NMR (400 MHz, CDCl₃/CD₃OD=5:1) δ 8.10 (s, 1H), 7.22-6.92 (m, 5H), 5.92 (d, J=5.4 Hz, 1H), 4.55-4.48 (m, 2H), 4.29 (t, J=3.7 Hz, 1H), 4.25-3.85 (m, 4H), 3.80-3.65 (m, 2H), 3.35-3.24 (m, 2H), 2.51 (s, 1H), 2.08-1.98 (m, 2H). ESI-MS (m/z): [M]⁺ calcd for C₂₆H₂₆ClN₅O₉, 588.14; found 588.2.

Example 66 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-(ethyl(methyl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except N-methylethanamine was used in place of benzylamine in step 7.

¹H NMR (400 MHz, CDCl₃/CD₃OD=5:1) δ 8.05 (s, 1H), 7.24-7.02 (m, 5H), 5.92 (d, J=4.8 Hz, 1H), 4.46 (dd, J=4.8, 1.3 Hz, 1H), 4.32 (dd, J=4.9, 3.2 Hz, 1H), 4.05 (dd, J=8.5, 4.0 Hz, 2H), 3.44-3.30 (m, 2H), 3.10-2.85 (m, 7H), 2.53 (s, 1H), 1.22 (t, J=7.1 Hz, 3H). ESI-MS (m/z): [M]⁺ calcd for C₂₅H₂₆ClN₅O₈, 560.15; found 560.5.

Example 67 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-((2-fluorobenzyl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except (2-fluorophenyl)methanamine was used in place of benzylamine in step 7.

¹H NMR (400 MHz, CDCl₃/CD₃OD=5:1) δ 8.29 (s, 1H), 7.47-7.36 (m, 1H), 7.26-6.94 (m, 8H), 5.94 (d, J=6.2 Hz, 1H), 4.82-4.76 (m, 2H), 4.60 (d, J=6.2 Hz, 1H), 4.35-4.23 (m, 1H), 3.98-3.84 (m, 2H), 3.44-3.30 (m, 2H), 2.46 (s, 1H). ESI-MS (m/z): [M]⁺ calcd for C₂₉H₂₅ClFN₅O₈, 626.14; found 626.7.

Example 68 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-((4-fluorobenzyl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except (4-fluorophenyl)methanamine was used in place of benzylamine in step 7.

¹H NMR (400 MHz, CDCl₃/CD₃OD=5:1) δ 8.49 (s, 1H), 7.37 (dd, J=8.4, 5.3 Hz, 2H), 7.24-6.89 (m, 7H), 5.97 (d, J=6.3 Hz, 1H), 4.72 (s, 2H), 4.63 (d, J=6.3 Hz, 1H), 4.7-4.28 (m, 1H), 4.06-3.87 (m, 2H), 3.46-3.26 (m, 2H), 2.54 (s, 1H). ESI-MS (m/z): [M]⁺ calcd for C₂₉H₂₅ClFN₅O₈, 626.14; found 626.4.

Example 69 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-(((R)-2,3-dihydro-1H-inden-1-yl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except (R)-2,3-dihydro-1H-inden-1-amine was used in place of benzylamine in step 7.

¹H NMR (400 MHz, CDCl₃/CD₃OD=5:1) δ 8.30 (s, 1H), 7.29-6.97 (m, 9H), 5.95 (d, J=6.2 Hz, 1H), 5.81 (t, J=7.1 Hz, 1H), 4.59 (d, J=6.3 Hz, 1H), 4.25 (d, J=3.1 Hz, 1H), 3.94-3.73 (m, 2H), 3.40-3.31 (m, 2H), 3.07 (ddd, J=14.0, 8.7, 4.8 Hz, 1H), 2.89 (dt, J=15.8, 7.7 Hz, 1H), 2.69-2.58 (m, 1H), 2.45 (s, 1H), 2.00 (dd, J=13.6, 7.1 Hz, 1H). ESI-MS (m/z): [M]⁺ calcd for C₃₁H₂₈ClN₅O₈, 634.16; found 634.8.

Example 70 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-(phenethylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except 2-phenylethan-1-amine was used in place of benzylamine in step 7.

¹H NMR (400 MHz, CDCl₃/CD₃OD=5:1) δ 8.14 (s, 1H), 7.26-6.91 (m, 10H), 5.91 (d, J=6.2 Hz, 1H), 4.57 (d, J=6.2 Hz, 1H), 4.27 (t, J=3.2 Hz, 1H), 3.96 (t, J=4.0 Hz, 2H), 3.78 (m, 2H), 3.45-3.29 (m, 2H), 2.93 (t, J=7.3 Hz, 2H), 2.52 (s, 1H). ESI-MS (m/z): [M]⁺ calcd for C₃₀H₂₈ClN₅O₈, 622.16; found 622.5.

Example 71 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-(methylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except methylamine was used in place of benzylamine in step 7.

¹H NMR (400 MHz, CD₃OD) δ 8.18 (s, 1H), 7.29-7.20 (m, 2H), 7.04 (dd, J=5.1, 1.9 Hz, 3H), 5.99 (d, J=7.4 Hz, 1H), 4.99 (d, J=7 Hz, 1H), 4.30 (t, J=3.3 Hz, 1H), 4.11-4.01 (m, 2H), 3.49-3.34 (m, 2H), 3.06 (s, 3H), 2.98 (s, 1H). ESI-MS (m/z): [M]⁺ calcd for C₂₃H₂₂ClN₅O₈, 532.12; found 532.1.

Example 72 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-(((S)-2,3-dihydro-1H-inden-1-yl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except (S)-2,3-dihydro-1H-inden-1-amine was used in place of benzylamine in step 7.

¹H NMR (400 MHz, CD₃OD) δ 8.14 (s, 1H), 7.41-7.13 (m, 6H), 7.04 (t, J=3.5 Hz, 3H), 6.01 (d, J=7.4 Hz, 1H), 5.88-5.76 (m, 1H), 4.99 (d, J=7.4 Hz, 1H), 4.32 (t, J=3.3 Hz, 1H), 4.06 (dd, J=5.5, 3.3 Hz, 2H), 3.53-3.34 (m, 2H), 3.13-3.05 (m, 1H), 3.00 (s, 1H), 2.99-2.87 (m, 1H), 2.67 (dd, J=12.5, 4.2 Hz, 1H), 2.02 (dd, J=12.8, 7.7 Hz, 1H). ESI-MS (m/z): [M]+ calcd for C₃₁H₂₈ClN₅O₈, 634.16; found 634.5.

Example 73 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-(ethylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except ethylamine was used in place of benzylamine in step 7.

¹H NMR (400 MHz, CD₃OD) δ 8.16 (s, 1H), 7.40-7.19 (m, 2H), 7.04 (dd, J=5.1, 1.9 Hz, 3H), 5.98 (d, J=7.4 Hz, 1H), 4.97 (d, J=7.4 Hz, 1H), 4.30 (T, J=3.3 Hz, 1H), 4.14-3.98 (m, 2H), 3.57 (d, J=7.8 Hz, 2H), 3.49-3.33 (m, 2H), 2.98 (s, 1H), 1.28 (t, J=7.2 Hz, 3H). ESI-MS (m/z): [M]⁺ calcd for C₂₄H₂₄ClN₅O₈, 546.13; found 546.1.

Example 74 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(6-((S)-sec-butylamino)-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except (S)-butan-2-amine was used in place of benzylamine in step 7.

¹H NMR (400 MHz, CD₃OD) δ 8.13 (s, 1H), 7.32-7.15 (m, 2H), 7.14-6.98 (m, 3H), 5.98 (d, J=7.4 Hz, 1H), 4.97 (d, J=7.4 Hz, 1H), 4.31 (t, J=3.2 Hz, 1H), 4.24 (s, 1H), 4.14-3.97 (m, 2H), 3.53-3.33 (m, 2H), 2.99 (s, 1H), 1.63 (q, J=7.2 Hz, 2H), 1.27 (d, J=6.5 Hz, 3H), 0.97 (t, J=7.4 Hz, 3H). ESI-MS (m/z): [M]⁺ calcd for C₂₆H₂₈ClN₅O₈, 574.16; found 574.1.

Example 75 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-((cyclopropylmethyl)-(methyl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except 1-cyclopropyl-N-methylmethanamine was used in place of benzylamine in step 7.

¹H NMR (400 MHz, CD₃OD) δ 8.15 (s, 1H), 7.36-7.18 (m, 2H), 7.03 (dd, J=5.2, 2.0 Hz, 3H), 6.00 (d, J=7.3 Hz, 1H), 4.97 (d, J=7.3 Hz, 1H), 4.30 (dd, J=4.1, 2.8 Hz, 1H), 4.07 (qd, J=10.2, 3.5 Hz, 2H), 3.52-3.31 (m, 7H), 2.98 (s, 1H), 1.20-1.12 (m, 1H), 0.54 (dd, J=8.2, 1.8 Hz, 2H), 0.45-0.30 (m, 2H). ESI-MS (m/z): [M]⁺ calcd for C₂₇H₂₈ClN₅O₈, 586.16; found 586.9.

Example 76 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(6-((carboxymethyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except 2-amino-N,N-dimethylacetamide was used in place of benzylamine in step 7.

¹H NMR (400 MHz, CD₃OD) δ 8.21 (s, 1H), 7.38-7.14 (m, 2H), 7.12-6.98 (m, 3H), 6.11 (d, J=7.4 Hz, 1H), 4.96 (d, J=7.3 Hz, 1H), 4.30 (q, J=4.7, 4.0 Hz, 2H), 4.09-4.02 (m, 2H), 3.54-3.33 (m, 2H), 2.97 (s, 1H). ESI-MS (m/z): [M]⁻ calcd for C₂₄H₂₂ClN₅O₁₀, 574.11; found 574.1.

Example 77 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-((2-chlorobenzyl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except (2-chlorophenyl)-methanamine was used in place of benzylamine in step 7.

¹H NMR (400 MHz, CD₃OD) δ 8.17 (s, 1H), 7.43 (m, 2H), 7.28 (m, 3H), 7.22 (m, 1H), 7.00 (m, 3H), 5.99 (d, J=7.4 Hz, 1H), 4.98 (d, J=7.4 Hz, 1H), 4.82 (m, 2H), 4.30 (s, 1H), 4.05 (s, 2H), 3.42 (m, 2H), 2.98 (s, 1H). LC-MS: m/z=597 (M-CO₂H); m/z=292 (M-ribose fragment).

Example 78 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-((pyridin-4-ylmethyl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except pyridin-4-ylmethanamine was used in place of benzylamine in step 7.

¹H NMR (400 MHz, CD₃OD) δ 9.08 (bs, 1H), 8.73 (d, J=5.7 Hz, 2H), 8.51 (s, 1H), 7.68 (d, J=5.6 Hz, 2H), 7.22 (m, 2H), 7.06 (m, 3H), 5.82 (d, J=7.7 Hz, 1H), 4.93 (d, J=6.9 Hz, 1H), 4.87 (d, J=7.6 Hz, 1H), 4.20 (m, 1H), 4.03 (m, 2H), 3.86 (m, 2H), 3.62 (s, 1H), 3.27 (m, 2H). HPLC: Room temperature=5.74 min, 97.7%. LC-MS: m/z=610 (M+); m/z=261 (M-ribose fragment).

Example 79 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-morpholino-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except morpholine was used in place of benzylamine in step 7.

¹H NMR (400 MHz, CD₃OD) δ 8.20 (s, 1H), 7.22 (m, 2H), 7.01 (m, 3H), 6.00 (d, J=7.6 Hz, 1H), 4.99 (d, J=7.6 Hz, 1H), 4.30 (m, 1H), 4.22 (m, 4H), 4.04 (m, 2H), 3.78 (m, 4H), 3.47 (m, 2H), 2.99 (s, 1H). HPLC: 8.16 min, 98.2%. LC-MS: m/z=588 (M+), 544 (M-CO₂H), m/z=240 (M-ribose fragment).

Example 80 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-(azepan-1-yl)-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-benzylmalonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except azepane was used in place of benzylamine in step 7.

¹H NMR (400 MHz, CD₃OD) δ 8.16 (s, 1H), 7.22 (m, 2H), 7.00 (m, 3H), 5.99 (d, J=7.6 Hz, 1H), 4.98 (d, J=7.6 Hz, 1H), 4.29 (m, 3H), 4.07 (m, 2H), 3.85 (m, 2H), 3.40 (m, 2H), 2.97 (s, 1H), 1.85 (m, 4H), 1.59 (m, 4H). HPLC: 9.67 min, 98.1%. LC-MS: m/z=600 (M+), m/z=556 (M-CO₂H), m/z=252 (M-ribose fragment).

Example 81 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-(cyclobutyl(methyl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except N-methylcyclobutanamine was used in place of benzylamine in step 7.

¹H NMR (400 MHz, CD₃OD) δ 8.21 (s, 1H), 7.21 (dd, J=7.0, 2.6 Hz, 2H), 6.99 (m, 3H), 5.99 (d, J=7.3 Hz, 1H), 5.74 (br s, 1H), 4.96 (d, J=7.2 Hz, 1H), 4.28 (dd, J=4.1, 2.8 Hz, 1H), 4.06 (dd, J=10.2, 4.2 Hz, 1H), 4.01 (dd, J=10.2, 2.9 Hz, 1H), 3.45-3.31 (m, 5H), 2.96 (s, 1H), 2.35 (q, J=10.0 Hz, 2H), 2.23 (m, 2H), 1.87-1.63 (m, 2H); HPLC: 9.45 min, 98.9%. LC-MS: m/z=587 (M+H), 543 (M-CO₂H), m/z=238 (M-ribose fragment).

Example 82 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-(isopropyl(methyl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except N-methylpropan-2-amine was used in place of benzylamine in step 7.

¹H NMR (400 MHz, CD₃OD) δ 8.17 (s, 1H), 7.21 (dd, J=7.3, 2.2 Hz, 2H), 7.03-6.94 (m, 3H), 5.98 (d, J=7.3 Hz, 1H), 4.97 (d, J=7.3 Hz, 1H), 4.28 (dd, J=4.0, 2.8 Hz, 1H), 4.04 (qd, J=10.2, 3.5 Hz, 2H), 3.45-3.31 (m, 6H), 2.96 (s, 1H), 1.25 (d, J=6.8 Hz, 6H); HPLC: 9.08 min, 99.9%. LC-MS: m/z=575 (M+H), 531 (M-CO₂H), m/z=226 (M-ribose fragment).

Example 83 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-(cyclopropylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except cyclopropanamine was used in place of benzylamine in step 7.

¹H NMR (400 MHz, CD₃OD) δ 8.14 (s, 1H), 7.23 (dd, J=6.7, 2.8 Hz, 2H), 7.01 (m, 3H), 5.97 (d, J=7.4 Hz, 1H), 4.95 (d, J=7.4 Hz, 1H), 4.28 (t, J=3.3 Hz, 1H), 4.10-3.97 (m, 2H), 3.49-3.30 (m, 2H), 2.99 (m, 1H), 2.96 (s, 1H), 0.92-0.78 (m, 2H), 0.66-0.54 (m, 2H); HPLC: 7.83 min, 99.1%. LC-MS: m/z=559 (M+H).

Example 84 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-((pyridin-3-ylmethyl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except pyridin-3-ylmethanamine was used in place of benzylamine in step 7.

¹H NMR (400 MHz, CD₃OD) δ 8.87 (s, 1H), 8.70 (d, J=5.6 Hz, 1H), 8.56 (d, J=8.1 Hz, 1H), 8.22 (s, 1H), 7.97 (dd, J=8.1, 5.7 Hz, 1H), 7.21 (dd, J=6.5, 3.0 Hz, 2H), 7.07-6.90 (m, 3H), 5.97 (d, J=7.4 Hz, 1H), 4.96 (d, J=7.4 Hz, 1H), 4.92 (m, 2H), 4.29 (t, J=3.4 Hz, 1H), 4.04 (qd, J=10.2, 3.4 Hz, 2H), 3.38 (m, 2H), 2.97 (s, 1H); HPLC: 5.82 min, 99.9%. LC-MS: m/z=261 (M-ribose fragment).

Example 85 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-((3-fluorobenzyl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except (3-fluorophenyl)methanamine was used in place of benzylamine in step 7.

¹H NMR (400 MHz, CD₃OD) δ 8.19 (s, 1H), 7.32 (td, J=8.0, 5.9 Hz, 1H), 7.24-7.16 (m, 3H), 7.12 (dd, J=9.8, 2.3 Hz, 1H), 7.06-6.78 (m, 4H), 5.98 (d, J=7.3 Hz, 1H), 4.94 (d, J=7.3 Hz, 1H), 4.74 (m, 2H), 4.29 (t, J=3.3 Hz, 1H), 4.03 (qd, J=10.3, 3.5 Hz, 2H), 3.47-3.26 (m, 2H), 2.97 (s, 1H); HPLC: 9.04 min, 99.5%. LC-MS: m/z=627 (M+H), 583 (M-CO₂H), m/z=278 (M-ribose fragment).

Example 86 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-((3-chlorobenzyl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except (3-chlorophenyl)methanamine was used in place of benzylamine in step 7.

¹H NMR (400 MHz, CD₃OD) δ 8.18 (s, 1H), 7.40 (s, 1H), 7.34-7.05 (m, 5H), 6.98 (m, 3H), 5.97 (d, J=7.4 Hz, 1H), 4.95 (d, J=7.4 Hz, 1H), 4.72 (m, 2H), 4.29 (t, J=3.3 Hz, 1H), 4.09-3.87 (m, 2H), 3.46-3.31 (m, 2H), 2.97 (s, 1H); HPLC: 9.45 min, 98.3%. LC-MS: m/z=643 (M+H), 598 (M-CO₂H), m/z=294 (M-ribose fragment).

Example 87 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-((4-chlorobenzyl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except (4-chlorophenyl)methanamine was used in place of benzylamine in step 7.

¹H NMR (400 MHz, CD₃OD) δ 8.17 (s, 1H), 7.36 (d, J=8.6 Hz, 2H), 7.31 (d, J=8.5 Hz, 1H), 7.21 (dd, J=6.8, 2.8 Hz, 2H), 7.02-6.96 (m, 3H), 5.97 (d, J=7.3 Hz, 1H), 4.94 (d, J=7.3 Hz, 1H), 4.71 (m, 2H), 4.29 (t, J=3.3 Hz, 1H), 4.03 (qd, J=10.2, 3.4 Hz, 2H), 3.46-3.30 (m, 2H), 2.96 (s, 1H); HPLC: 9.50 min, 98.7%. LC-MS: m/z=643 (M+H), 598 (M-CO₂H), m/z=294 (M-ribose fragment).

Example 88 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-(azetidin-1-yl)-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-benzylmalonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except azetidine was used in place of benzylamine in step 7.

¹H NMR (400 MHz, CD₃OD) δ 8.25 (s, 1H), 7.24-7.08 (m, 2H), 7.10-6.85 (m, 3H), 5.97 (d, J=7.4 Hz, 1H), 4.98 (d, J=7.3 Hz, 1H), 4.43 (m, 4H), 4.29 (dd, J=4.1, 2.8 Hz, 1H), 4.07 (dd, J=10.2, 4.2 Hz, 1H), 4.00 (dd, J=10.2, 2.9 Hz, 1H), 3.42 (d, J=15.0 Hz, 1H), 3.34 (d, J=12.3 Hz, 2H), 2.95 (s, 1H), 2.51 (q, J=7.7 Hz, 2H); HPLC: 7.58 min, 99.5%. LC-MS: m/z=558 (M+H), 554 (M-CO₂H), m/z=210 (M-ribose fragment).

Example 89 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-(dimethylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except dimethylamine was used in place of benzylamine in step 7.

¹H NMR (400 MHz, CD₃OD) δ 8.17 (s, 1H), 7.22 (dd, J=7.5, 2.0 Hz, 2H), 7.05-6.89 (m, 3H), 5.98 (d, J=7.2 Hz, 1H), 4.96 (d, J=7.3 Hz, 1H), 4.28 (dd, J=4.0, 2.9 Hz, 1H), 4.04 (qd, J=10.2, 3.5 Hz, 2H), 3.55-3.31 (m, 8H), 2.95 (s, 1H); HPLC: 8.16 min, 99.9%. LC-MS: m/z=546 (M+H), 502 (M-CO₂H), m/z=198 (M-ribose fragment).

Example 90 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-(pyrrolidin-1-yl)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except pyrrolidine was used in place of benzylamine in step 7.

¹H NMR (400 MHz, CD₃OD) δ 8.21 (s, 1H), 7.21 (dd, J=7.3, 2.3 Hz, 2H), 7.03-6.76 (m, 3H), 5.98 (d, J=7.3 Hz, 1H), 4.98 (d, J=7.3 Hz, 1H), 4.29 (dd, J=4.2, 2.8 Hz, 1H), 4.15-3.86 (m, 4H), 3.66 (m, 2H), 3.41 (d, J=15.0 Hz, 1H), 3.34 (d, J=15.0 Hz, 1H), 2.95 (s, 1H), 2.02 (m, 4H); HPLC: 8.42 min, 95.6%. LC-MS: m/z=573 (M+H), 529 (M-CO₂H), m/z=224 (M-ribose fragment).

Example 91 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-(cyclopentylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except cyclopentanamine was used in place of benzylamine in step 7.

¹H NMR (400 MHz, CD₃OD) δ 8.09 (s, 1H), 7.23 (dd, J=6.7, 2.9 Hz, 2H), 7.01 (m, 3H), 5.96 (d, J=7.4 Hz, 1H), 4.94 (d, J=7.4 Hz, 1H), 4.47 (m, 1H), 4.28 (t, J=3.3 Hz, 1H), 4.04 (m, 2H), 3.43 (d, J=14.9 Hz, 1H), 3.34 (d, J=14.9 Hz, 1H), 2.96 (s, 1H), 2.19-1.98 (m, 2H), 1.78 (m, 2H), 1.72-1.64 (m, 2H), 1.62-1.52 (m, 2H); HPLC: 9.06 min, 98.9%. LC-MS: m/z=587 (M+H), 543 (M-CO₂H), m/z=238 (M-ribose fragment).

Example 92 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-((cyclopropylmethyl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except cyclopropylmethanamine was used in place of benzylamine in step 7.

¹H NMR (400 MHz, CD₃OD) δ 8.14 (s, 1H), 7.18 (d, J=6.9 Hz, 2H), 7.12-6.68 (m, 3H), 5.92 (d, J=6.1 Hz, 1H), 4.58 (d, J=6.1 Hz, 1H), 4.28 (t, J=3.2 Hz, 1H), 3.98 (qd, J=10.3, 3.2 Hz, 2H), 3.50-3.04 (m, 4H), 2.55 (s, 1H), 1.08 (m, 1H), 0.52 (m, 2H), 0.26 (m, 2H); HPLC: 8.52 min, 97.7%. LC-MS: m/z=572 (M+H), 528 (M-CO₂H), m/z=224 (M-ribose fragment).

Example 93 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-(isopropylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except propan-2-amine was used in place of benzylamine in step 7.

¹H NMR (400 MHz, CD₃OD) δ 8.05 (s, 1H), 7.23-7.12 (m, 2H), 7.09-6.78 (m, 3H), 5.91 (d, J=6.2 Hz, 1H), 4.59 (d, J=6.2 Hz, 1H), 4.37 (m, 1H), 4.28 (m, 1H), 3.42 (d, J=14.8 Hz, 1H), 3.35-3.22 (m, 3H), 2.56 (s, 1H), 1.24 (d, J=6.5 Hz, 6H); HPLC: 8.39 min, 98.9%. LC-MS: m/z=560 (M+H), 516 (M-CO₂H), m/z=212 (M-ribose fragment).

Example 94 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-((2-hydroxy-2-methylpropyl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except 1-amino-2-methylpropan-2-ol was used in place of benzylamine in step 7.

¹H-NMR (400 MHz, CD₃OD) δ 8.16 (s, 1H) 7.24-7.22 (m, 2H) 7.03-7.01 (m, 3H) 5.97 (d, J=7.4 Hz, 1H) 4.95 (d, J=7.4 Hz, 1H) 4.28 (t, J=3.2 Hz, 1H) 4.05-4.03 (m, 2H) 3.72-3.69 (m, 2H) 3.48-3.31 (m, 2H) 2.97 (s, 1H) 1.24 (s, 6H). ESI-MS (m/z): [M]⁻ calcd for C₂₆H₂₈ClN₅O₉ 589.98; found 588.4.

Example 95 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-(((S)-1-hydroxypropan-2-yl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except (S)-2-aminopropan-1-ol was used in place of benzylamine in step 7.

¹H-NMR (400 MHz, CD₃OD) δ 8.18 (s, 1H) 7.24-7.22 (m, 2H) 7.03-7.01 (m, 3H) 5.97 (d, J=7.4 Hz, 1H) 4.93 (d, J=7.4 Hz, 1H) 4.42-4.35 (m, 1H) 4.32-4.26 (m, 1H) 4.04 (d, J=3.2 Hz, 2H) 3.62-3.60 (m, 2H) 3.48-3.32 (m, 2H) 2.96 (s, 1H) 1.29 (d, J=6.7 Hz, 3H). ESI-MS (m/z): [M]⁻ calcd for C₂₅H₂₆ClN₅O₉ 575.96; found 574.2.

Example 96 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-(diethylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except diethylamine was used in place of benzylamine in step 7.

¹H-NMR (400 MHz, CD₃OD) δ 8.15 (s, 1H) 7.23-7.20 (m, 2H) 7.00-6.98 (m, 3H) 5.98 (d, J=7.3 Hz, 1H) 4.97 (d, J=7.3 Hz, 1H) 4.29 (m, 1H) 4.15-3.83 (m, 6H) 3.43-3.33 (m, 2H) 2.96 (s, 1H) 1.24 (t, J 7.0 Hz, 6H). ESI-MS (m/z): [M]⁻ calcd for C₂₆H₂₈ClN₅8₉ 573.98; found 572.3.

Example 97 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-((2-hydroxyethyl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except 2-aminoethan-1-ol was used in place of benzylamine in step 7.

¹H-NMR (400 MHz, CD₃OD) δ 8.20 (s, 1H) 7.24-7.22 (m, 2H) 7.04-7.02 (m, 3H) 5.97 (d, J=7.4 Hz, 1H) 4.91 (d, J=7.3 Hz, 1H) 4.29 (t, J=3.4 Hz, 1H)) 4.06-3.98 (m, 2H) 3.76-3.73 (m, 2H) 3.66-3.63 (m, 2H) 3.43-3.33 (m, 2H) 2.96 (s, 1H). ESI-MS (m/z): [M]⁻ calcd for C₂₄H₂₄ClN₅O₉ 561.93; found 560.2.

Example 98 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-(((R)-1-hydroxypropan-2-yl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except (R)-2-aminopropan-1-ol was used in place of benzylamine in step 7.

¹H-NMR (400 MHz, CD₃OD) δ 8.12 (s, 1H) 7.24-7.22 (m, 2H) 7.03-7.01 (m, 3H) 5.96 (d, J=7.4 Hz, 1H) 4.95 (d, J=7.4 Hz, 1H) 4.42-4.32 (m, 1H) 4.28 (t, J=3.3 Hz, 1H) 4.08-4.00 (m, 2H) 3.66-3.58 (m, 2H) 3.45-3.33 (m, 2H) 2.97 (s, 1H) 1.27 (d, J=6.7 Hz, 3H). ESI-MS (m/z): [M]⁻ calcd for C₂₅H₂₆ClN₅O₉ 575.96; found 574.2.

Example 99 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-(cyclopropyl(2-hydroxyethyl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except 2-(cyclopropylamino)ethan-1-ol was used in place of benzylamine in step 7.

¹H-NMR (400 MHz, CD₃OD) δ 8.23 (s, 1H) 7.24-7.22 (m, 2H) 7.04-7.01 (m, 3H) 6.02 (d, J=7.4 Hz, 1H) 4.96 (d, J=7.3 Hz, 1H) 4.30-4.28 (m, 1H) 4.10-4.04 (m, 4H) 3.78 (t, J=5.9 Hz, 2H) 3.44-3.32 (m, 2H) 3.23-3.19 (m, 1H) 2.96 (s, 1H) 1.01-0.97 (m, 2H) 0.78-0.74 (m, 2H).

Example 100 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-((R)-3-hydroxypyrrolidin-1-yl)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except (R)-pyrrolidin-3-ol was used in place of benzylamine in step 7.

¹H NMR (400 MHz, CD₃OD) δ 8.24 (s, 1H), 7.23 (d, J=7.2 Hz, 2H), 7.06-6.96 (m, 3H), 6.01 (d, J=7.3 Hz, 1H), 5.01 (s, 1H), 4.56 (d, J=26.1 Hz, 1H), 4.33-4.31 (m, 1H), 4.20 (d, J=12.5 Hz, 1H), 4.10-4.00 (m, 3H), 3.78 (m, 2H), 3.50-3.35 (m, 2H), 2.97 (s, 1H), 2.14-2.05 (m, 2H).

Example 101 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-((S)-3-(hydroxymethyl)-pyrrolidin-1-yl)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except (S)-pyrrolidin-3-ylmethanol was used in place of benzylamine in step 7.

¹H NMR (400 MHz, DMSO-d₆) δ 8.37 (s, 1H), 8.34 (s, 1H), 7.15 (m, 2H), 7.01 (m, 3H), 6.16 (br s, 1H), 5.96 (br s, 1H), 5.81 (d, J=7.5 Hz, 1H), 4.82 (d, J=7.4 Hz, 1H), 4.18-4.08 (m, 1H), 3.94 (m, 2H), 3.71 (m, 2H), 3.50 (m, 2H), 3.20 (s, 4H), 3.13 (s, 1H), 2.33 (m, 1H), 2.04 (m, 1H), 1.98-1.89 (m, 1H), 1.77 (m, 1H), 1.65 (m, 1H); HPLC: 7.22 min, 97.7%.

Example 102 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-((R)-3-(hydroxymethyl)-pyrrolidin-1-yl)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except (R)-pyrrolidin-3-ylmethanol was used in place of benzylamine in step 7.

¹H NMR (400 MHz, DMSO-d₆) δ 8.37 (s, 1H), 8.34 (s, 1H), 7.21-7.11 (m, 2H), 7.01 (m, 3H), 6.16 (br s, 1H), 5.96 (br s, 1H), 5.81 (d, J=7.5 Hz, 1H), 4.82 (d, J=7.5 Hz, 1H), 4.44 (m, 1H), 4.25-4.07 (m, 3H), 3.95 (m, 2H), 3.87-3.64 (m, 3H), 3.51 (m, 2H), 3.20 (s, 1H), 2.37-2.27 (m, 1H), 2.04 (m, 1H), 1.98-1.86 (m, 1H), 1.76 (m, 1H), 1.66 (m, 1H); HPLC: Rt=7.20 min, 97.0%.

Example 103 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-((R)-2-(hydroxymethyl)-pyrrolidin-1-yl)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except (R)-pyrrolidin-2-ylmethanol was used in place of benzylamine in step 7.

¹H NMR (400 MHz, CD₃OD) δ 8.21 (s, 1H), 7.28-7.16 (m, 2H), 7.08-6.87 (m, 3H), 5.99 (d, J=7.3 Hz, 1H), 4.97 (d, J=7.3 Hz, 1H), 4.41 (m, 1H), 4.28 (m, 1H), 4.12-3.93 (m, 4H), 3.72 (m, 2H), 3.42 (d, J=15.0 Hz, 1H), 3.33 (d, J=15.0 Hz, 2H), 2.96 (s, 1H), 2.05 (m, 4H); HPLC: 7.73 min, 98.2%; ESI-MS: m/z=254 (M-ribose fragment).

Example 104 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-((S)-2-(hydroxymethyl)-pyrrolidin-1-yl)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except (S)-pyrrolidin-2-ylmethanol was used in place of benzylamine in step 7.

¹H NMR (400 MHz, CD₃OD) δ 8.22 (s, 1H), 7.22 (m, 2H), 7.07-6.88 (m, 3H), 5.99 (d, J=7.3 Hz, 1H), 4.98 (d, J=7.3 Hz, 1H), 4.44 (m, 1H), 4.29 (dd, J=4.0, 2.9 Hz, 1H), 4.07 (m, 2H), 4.05 (qd, J=10.2, 3.5 Hz, 2H), 3.77 (dd, J=11.0, 4.2 Hz, 1H), 3.66 (dd, J=11.1, 6.5 Hz, 1H), 3.42 (d, J=15.1 Hz, 1H), 3.33 (d, J=15.1 Hz, 1H), 2.95 (s, 1H), 2.07 (m, 4H); HPLC: 7.77 min, 99.3%; ESI-MS: m/z=642 (M+ACN).

Example 105 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-(cyclopropyl(methyl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except N-methylcyclopropanamine was used in place of benzylamine in step 7.

¹H NMR (400 MHz, CD₃OD) δ 8.36 (s, 1H), 7.26-7.12 (m, 2H), 7.02 (m, 3H), 6.03 (d, J=7.3 Hz, 1H), 4.97 (d, J=7.3 Hz, 1H), 4.30 (dd, J=3.9, 2.8 Hz, 1H), 4.19-3.97 (m, 2H), 3.57-3.29 (m, 5H), 3.21 (m, 1H), 2.96 (s, 1H), 1.05-0.85 (m, 2H), 0.83-0.62 (m, 2H); HPLC: Rt=8.41 min, 98.6%; ESI-MS: m/z=224 (M-ribose fragment).

Example 106 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-((cyclopropylmethyl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-(methylamino)-3-oxopropanoic acid

Step 1:

A stirred solution of [(3aR,5R,6R,6aR)-6-ethynyl-6-(methoxymethoxy)-2,2-dimethyl-tetrahydro-2H-furo[2,3-d][1,3]dioxol-5-yl]methanol (480 mg, 1.87 mmol) and methyl 2-diazo-2-(methylcarbamoyl)acetate (440 mg, 2.8 mmol, prepared according to literature: European Journal of Organic Chemistry, 2014 (24), 5302-5311) in anhydrous benzene (20 mL) under nitrogen was treated with rhodium tetraacetate (16 mg, 0.04 mmol) and heated to 60° C. for 4 h. The resulting mixture was cooled to room temperature and concentrated. The resulting oil was dissolved in dichloromethane, loaded onto a silica gel column eluting with 10-100% ethyl acetate in hexane to afford methyl 2-{[(3aR,5R,6R,6aR)-6-ethynyl-6-(methoxymethoxy)-2,2-dimethyl-tetrahydro-2H-furo[2,3-d][1,3]dioxol-5-yl]methoxy}-2-(methylcarbamoyl)acetate (455 mg, 63% yield) as a diastereomeric pair.

Step 2:

A solution of methyl 2-{[(3aR,5R,6R,6aR)-6-ethynyl-6-(methoxymethoxy)-2,2-dimethyl-tetrahydro-2H-furo[2,3-d][1,3]dioxol-5-yl]methoxy}-2-(methylcarbamoyl)acetate (450 mg, 116 mmol) and benzyl bromide (0.97 mL, 8.13 mmol) in anhydrous DMF (4 mL) was treated with cesium carbonate (757 mg, 2.32 mmol). The reaction mixture was stirred at room temperature overnight. The reaction was quenched with water (10 mL), diluted with diethyl ether (70 mL) and washed with saturated aqueous sodium chloride (50 mL) twice. The organic layer was dried with NaSO₄ and concentrated to give a yellow oil. The residue was purified by silica gel column and eluted with 10-70% ethyl acetate in hexane to afford a diastereomeric mixture methyl 2-benzyl-2-(((3aR,5R,6R,6aR)-6-ethynyl-6-(methoxy-methoxy)-2,2-dimethyltetrahydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)-3-(methylamino)-3-oxopropanoate (500 mg, 90% yield) as a clear oil as.

Step 3:

While under nitrogen, an ice cooled stirred solution of methyl 2-benzyl-2-(((3aR,5R,6R,6aR)-6-ethynyl-6-(methoxymethoxy)-2,2-dimethyltetrahydrofuro[2,3-d][1,3]-dioxol-5-yl)methoxy)-3-(methylamino)-3-oxopropanoate (500 mg, 1.05 mmol) in acetic acid (4 mL) was treated with acetic anhydride (1 mL, 11.15 mmol) and concentrated sulfuric acid (0.02, 0.35 mmol). The reaction solution was slowly warmed to room temperature. After 4 hours, reaction was diluted with water and extracted with ethyl acetate (80 mL each). The organic solution was washed with saturated sodium bicarbonate (100 mL), dried over Na₂SO₄ and concentrated. The residual oil was dissolved in dichloromethane and purified by flash chromatography to provide (3R,4R,5R)-5-(((2-benzyl-1-methoxy-3-(methylamino)-1,3-dioxopropan-2-yl)oxy)methyl)-4-ethynyltetrahydrofuran-2,3,4-triyl triacetate as an anomer/diastereomeric mixture.

Step 4:

A suspension of 2-6-dichloroadenine (48 mg, 0.25 mmol) and N,O-bis(trimethylsilyl)-acetamide (0.08 mL, 0.32 mmol) in anhydrous acetonitrile (7 mL) was treated with a second solution of (3R,4R,5R)-5-(((2-benzyl-1-methoxy-3-(methylamino)-1,3-dioxopropan-2-yl)oxy)methyl)-4-ethynyltetrahydrofuran-2,3,4-triyl triacetate (130 mg, 0.25 mmol) in anhydrous acetonitrile (10 mL), followed by dropwise addition of trimethylsilyl trifluoromethanesulfonate (0.06 mL, 0.33 mmol). Once the addition was complete, the reaction was heated to 50° C. for 18 h, cooled to room temperature and quenched with saturated sodium bicarbonate solution (80 mL). After stirring for a 5 minutes the solution was extracted with ethyl acetate (3×80 mL), dried over Na₂SO₄ and concentrated. The residue was dissolved in dichloromethane and purified by flash chromatography to provide (2R,3R,4R,5R)-2-(((2-benzyl-1-methoxy-3-(methylamino)-1,3-dioxopropan-2-yl)oxy)methyl)-5-(2,6-dichloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate (135 mg, 83% yield) as a foamy solid (diastereomer pair).

Step 5:

While under nitrogen, a solution of (2R,3R,4R,5R)-2-(((2-benzyl-1-methoxy-3-(methylamino)-1,3-dioxopropan-2-yl)oxy)methyl)-5-(2,6-dichloro-9H-purin-9-yl)-3-ethynyl-tetrahydrofuran-3,4-diyl diacetate (70 mg, 0.11 mmol) in dioxane (2 mL) was cooled to 0° C. and treated with diisopropylethylamine (0.03 mL, 0.16 mmol) and cyclopropylamine (0.01 mL, 0.13 mmol), and warmed to room temperature with stirring overnight. The reaction mixture was diluted with ethyl acetate (80 mL), washed with water (50 mL) and saturated aqueous sodium chloride (50 mL). The organic layer was dried over Na₂SO₄ then filtered and concentrated. The residue was dissolved in dichloromethane and purified by flash column chromatography to afford (2R,3R,4R,5R)-2-(((2-benzyl-1-methoxy-3-(methylamino)-1,3-dioxopropan-2-yl)oxy)methyl)-5-(2-chloro-6-((cyclopropylmethyl)amino)-9H-purin-9-yl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate (70 mg, 95% yield) as an off-white solid (diastereomeric pair).

Step 6:

To solution of (2R,3R,4R,5R)-2-(((2-benzyl-1-methoxy-3-(methylamino)-1,3-dioxo-propan-2-yl)oxy)methyl)-5-(2-chloro-6-((cyclopropylmethyl)amino)-9H-purin-9-yl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate (70 mg, 0.10 mmol) in THF (1 mL) was treated with LiOH (24 mg, 1.02 mmol) in water (1 mL) and stirred at room temperature overnight. Reaction pH was adjusted to 4-5 using cold 2 N HCl. Upon precipitation, the suspension was stirred for another 10 min. The solid was collected, washed with cold water and dried to provide 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-((cyclopropylmethyl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydro-furan-2-yl)methoxy)-3-(methylamino)-3-oxopropanoic acid (45 mg, 75% yield) as an off-white solid (diastereomeric pair).

¹H NMR (400 MHz, CDCl₃/CD₃OD=5:1) δ 8.01 (s, 0.45H), 7.48 (s, 0.55H), 7.22-7.03 (m, 5H), 5.86 (dd, J=4.7, 3.0 Hz, 1H), 4.43 (dd, J=8.5, 4.6 Hz, 1H), 4.31-4.06 (m, 2H), 3.84-3.72 (m, 1H), 3.45-3.21 (m, 4H), 2.62 (d, J=40.9 Hz, 1H), 2.46 (d, J=8.1 Hz, 3H), 1.05 (dq, J=8.0, 3.7 Hz, 1H), 0.51 (ddd, J=8.1, 4.0, 1.6 Hz, 2H), 0.31-0.18 (m, 2H). ESI-MS (m/z): [M]⁺ calcd for C₂₇H₂₉ClN₆O₇, 585.18; found 585.9.

Example 107 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(6-(benzylamino)-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-(methylamino)-3-oxopropanoic acid

The title compound was prepared in a manner analogous to that set forth in Example 106, except benzylamine was used in place of cyclopropylamine in step 5.

¹H NMR (400 MHz, CDCl₃/CD₃OD=5:1) δ 8.03 (s, 0.46H), 7.52 (d, J=2.7 Hz, 0.54H), 7.42-7.04 (m, 10H), 5.89 (t, J=4.3 Hz, 1H), 4.73 (m, 2H), 4.44 (dd, J=6.0, 4.5 Hz, 1H), 4.33-4.15 (m, 2H), 3.79 (dd, J=10.6, 4.5 Hz, 1H), 3.45-3.27 (m, 2H), 2.62 (d, J=36.6 Hz, 1H), 2.48 (d, J=13.2 Hz, 3H). ESI-MS (m/z): [M]⁺ calcd for C₃₀H₂₉ClN₆O₇, 621.18; found 621.4.

Example 108 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-((2-chlorobenzyl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-ethoxy-3-oxopropanoic acid

The title compounds is prepared in a manner analogous to that set forth in Example 59, except only 5 equivalents of lithium hydroxide are used in step 8.

¹H NMR (400 MHz, CD₃OD) δ 8.16 (s, 1H), 7.42 (m, 2H), 7.26 (m, 2H), 7.21 (m, 2H), 6.99 (m, 3H), 5.97 (d, J=7.6 Hz, 1H), 4.96 (d, J=7.6 Hz, 1H), 4.82 (m, 2H), 4.28 (m, 1H), 4.03 (m, 2H), 3.75 (m, 2H), 3.38 (m, 2H), 3.22 (m, 2H), 2.97 (s, 1H) 1.29 (t, J=7.6 Hz, 3H). HPLC: 9.43 min, 96.2%. LC-MS: m/z=642, 597 (M-CO₂H); m/z=292 (M-ribose fragment).

Example 109 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-((pyridin-4-ylmethyl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-ethoxy-3-oxopropanoic acid

The title compounds is prepared in a manner analogous to that set forth in Example 59, except only 5 equivalents of lithium hydroxide are used in step 8. Compound was isolated as ˜2:1 mixture of diastereomers.

¹H NMR (400 MHz, DMSO-d₆) of major isomer: δ 8.73 (d, J=5.9 Hz, 2H), 8.15 (s, 0.61H), 7.98 (d, J=5.9 Hz, 2H), 7.23 (m, 2H), 7.06 (m, 3H), 6.00 (m, 1H), 5.00 (m, 2H), 4.10 (m, 4H), 3.39 (m, 2H), 3.12 (s, 0.80H), 1.17 (m, 3H). 1H NMR (DMSO-d₆) of minor isomer: δ 8.73 (d, J=5.9 Hz, 2H), 8.31 (s, 0.32H), 7.98 (d, J=5.9 Hz, 2H), 7.23 (m, 2H), 7.06 (m, 3H), 6.00 (m, 1H), 5.00 (m, 2H), 4.10 (m, 4H), 3.39 (m, 2H), 3.01 (s, 0.41H), 1.17 (m, 3H). HPLC: 6.25 min, 94.8%. LC-MS: m/z=638 (M+), 594 (M-CO₂H), m/z=259 (M-ribose fragment).

Example 110 Synthesis of 2-(((2R,3S,4R,5R)-5-(2-chloro-6-(isopropylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-((5-methylisoxazol-3-yl)methyl)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except 3-(bromomethyl)-5-methylisoxazole was used in place of benzyl bromide in step 4 and propan-2-amine is used in place of benzylamine in step 7.

¹H-NMR (400 MHz, CD₃OD) δ 8.46 (s, 1H) 5.99 (d, J 7.6 Hz, 1H) 5.95 (s, 1H) 5.07 (d, J=7.6 Hz, 1H) 4.41-4.38 (m, 1H) 4.31-4.29 (m, 1H) 4.07-4.05 (m, 1H) 3.99-3.88 (m, 1H) 3.50-3.38 (m, 2H) 2.95 (s, 1H) 2.05 (s, 3H) 1.27 (d, J=6.5 Hz, 6H). ESI-MS (m/z): [M]⁺ calcd for C₂₃H₂₅ClN₆O₉ 564.93; found 566.1.

Example 111 Synthesis of 2-(((2R,3S,4R,5R)-5-(2-chloro-6-((4-fluorobenzyl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-((5-methylisoxazol-3-yl)methyl)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except 3-(bromomethyl)-5-methylisoxazole was used in place of benzyl bromide in step 4 and (4-fluorophenyl)methanamine is used in place of benzylamine in step 7.

¹H-NMR (400 MHz, CD₃OD) δ 8.62-8.58 (br s, 1H) 7.41-7.38 (m, 2H) 7.07-7.01 (m, 2H) 6.01 (d, J=7.4 Hz, 1H) 5.96 (s, 1H) 5.09 (d, J=7.3 Hz, 1H) 4.82-4.71 (m, 2H) 4.31-4.29 (m, 1H) 4.06 (dd, J=10.0, 3.8 Hz, 1H) 3.97 (dd, J=10.1, 3.1 Hz, 1H) 3.44-3.32 (m, 2H) 3.18 (s, 3H) 2.96 (s, 1H).

Example 112 Synthesis of 2-(benzo[d]thiazol-2-ylmethyl)-2-(((2R,3S,4R,5R)-5-(2-chloro-6-((4-fluorobenzyl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except 2-(bromomethyl)benzo[d]thiazole is used in place of benzyl bromide in step 4 and (4-fluorophenyl)methanamine was used in place of benzylamine in step 7.

¹H-NMR (400 MHz, CD₃OD) δ 8.57-8.54 (br s, 1H) 7.74-7.70 (m, 2H) 7.45-7.41 (m, 2H) 7.23-7.20 (m, 1H) 7.12-7.16 (m, 1H) 7.09-7.04 (m, 2H) 5.94 (d, J=7.3 Hz, 1H) 5.15 (d, J=7.1 Hz, 1H) 4.77-4.72 (m, 2H) 4.35-4.32 (m, 1H) 4.20 (dd, J=10.1, 2.7 Hz, 1H) 4.11 (dd, J=10.1, 3.1 Hz, 1H) 3.99-3.86 (m, 2H) 2.77 (s, 1H).

Example 113 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-oxo-3-(pyrrolidin-1-yl)propanoic acid

The title compound was prepared in an analogous manner to Example 59 except ethyl 2-diazo-3-oxo-3-(pyrrolidin-1-yl)propanoate was used instead of 1-ethyl 3-(prop-1-en-1-yl) 2-diazomalonate in Step 3 and ammonia is used in place of benzylamine in Step 7. The product is isolated as a 55/45 mixture of diastereomers.

Major diastereomer ¹H-NMR (400 MHz, CD₃OD) δ 8.80 (s, 1H) 5.99 (d, J=7.4 Hz, 1H) 5.05 (d, J=7.4 Hz, 1H) 4.88 (s, 1H) 4.28-4.26 (m, 1H) 4.13 (dd, J=10.7, 2.5 Hz, 1H) 4.00 (dd, J=10.7, 3.9 Hz, 1H) 3.66-3.39 (m, 4H) 3.17 (s, 1H) 1.89-1.79 (m, 4H). Minor diasteromer 1H-NMR (400 MHz, CD₃OD) δ 8.89 (s, 1H) 6.03 (d, J=7.4 Hz, 1H) 5.05 (d, J=7.4 Hz, 1H) 4.86 (s, 1H) 4.28-4.26 (m, 1H) 3.90-3.86 (m, 2H) 3.66-3.39 (m, 4H) 3.16 (s, 1H) 1.89-1.79 (m, 4H). ESI-MS (m/z): [M]⁻ calcd for C₁₉H₂₁ClN₆O₇ 480.86; found 479.1.

Example 114 Synthesis of 2-(((2R,3S,4R,5R)-5-(2-chloro-6-(cyclopentylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-oxo-3-(pyrrolidin-1-yl)propanoic acid

The title compound was prepared in an analogous manner to Example 59 except ethyl 2-diazo-3-oxo-3-(pyrrolidin-1-yl)propanoate was used instead of 1-ethyl 3-(prop-1-en-1-yl) 2-diazomalonate in Step 3 and cyclopentanamine is used in place of benzylamine in Step 7. The product is isolated as a 55/45 mixture of diastereomers.

Major diastereomer. ¹H NMR (400 MHz, CD₃OD) δ 8.72 (s, 1H) 5.96 (d, J=7.4 Hz, 1H) 5.04 (d, J=7.4 Hz, 1H) 4.87 (s, 1H) 4.52-4.48 (m, 1H) 4.28-4.25 (m, 1H) 4.14 (d, J=10.5 Hz, 1H) 4.01 (dd, J=10.6, 5.2 Hz, 1H) 3.60-3.36 (m, 4H) 3.17 (s, 1H) 2.10-2.04 (m, 2H) 1.84-1.77 (m, 6H) 1.69-1.58 (m, 4H) Minor diastereomer ¹H NMR (400 MHz, CD₃OD) δ 8.64 (s, 1H) 6.00 (d, J=7.4 Hz, 1H) 5.01 (d, J=7.4 Hz, 1H) 4.85 (s, 1H) 4.52-4.48 (m, 1H) 4.28-4.25 (m, 1H) 3.92-3.86 (m, 2H) 3.60-3.36 (m, 4H) 3.16 (s, 1H) 2.10-2.04 (m, 2H) 1.84-1.77 (m, 6H) 1.69-1.58 (m, 4H) (ESI-MS (m/z): [M]⁻ calcd for C₂₄H₂₉ClN₆O₇ 548.98; found 547.3.

Example 115 Synthesis of 3-amino-2-(((2R,3S,4R,5R)-5-(2-chloro-6-(cyclopentylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-oxopropanoic acid

Step 1:

While under nitrogen, a suspension of 2,6-dichloroadenine (2.91 g, 15.4 mmoL, 1.01 eq) and N,O-bis(trimethylsilyl)acetamide (4.87 mL, 19.6 mmoL, 1.29 eq) in anhydrous acetonitrile (90 mL). Next, a solution of (2R,3R,4R,5R)-2,4-bis(acetyloxy)-5-{[(tert-butyldiphenylsilyl)oxy]methyl}-4-ethynyloxolan-3-yl acetate (8.2 g, 15.22 mmoL) in anhydrous acetonitrile (10 mL) was added, followed by dropwise addition of trimethylsilyl trifluoromethanesulfonate (3.67 mL, 20.3 mmoL, 1.33 eq). The reaction was warmed to 50° C. for 18 h, then cooled to room temperature. (Reaction begins a pale-yellow color and after 4 h turns to a transparent amber). Saturated aqueous sodium bicarbonate (10 mL), was added and the mixture was stirred for ten minutes. The resulting mixture was extracted with ethyl acetate (3×100 mL) and the combined organic layer was dried (Na₂SO₄), filtered, and concentrated. The residue was dissolved in dichloromethane/ethyl acetate (˜3 mL, 1:1), loaded onto a silica gel column (˜300 cc), and eluted with 0-30% ethyl acetate in hexanes to provide (2R,3R,4R,5R)-2-(((tert-butyldiphenylsilyl)oxy)methyl)-5-(2,6-dichloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate (8.2 g, 81%) as a white solid.

Step 2:

A solution of (2R,3R,4R,5R)-2-(((tert-butyldiphenylsilyl)oxy)methyl)-5-(2,6-dichloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate (1.6 g, 2.4 mmoL) in anhydrous THF (25 mL) was cooled to 0° C. and treated with acetic acid (0.192 mL, 3.36 mmoL, 1.4 eq) a 1 N solution of tetrabutylammonium fluoride in THF (3.36 mL, 3.36 mmoL, 1.4 eq). After the addition was complete, the reaction was warmed to room temperature with stirring for 3 h. The reaction mixture was concentrated, a purified via flash column chromatography (0 to 50% ethyl acetate in hexanes to afford (2R,3R,4R,5R)-5-(2,6-dichloro-9H-purin-9-yl)-3-ethynyl-2-(hydroxymethyl)tetrahydrofuran-3,4-diyl diacetate (0.88 g, 86%) as a white foam.

Step 3:

While under nitrogen, a solution of ((2R,3R,4R,5R)-5-(2,6-dichloro-9H-purin-9-yl)-3-ethynyl-2-(hydroxymethyl)tetrahydrofuran-3,4-diyl diacetate (172 mg, 0.40 mmol) and ethyl 3-(aminooxy)-2-diazo-3-oxopropanoate (160 mg, 1.02 mmoL, 2.5 eq) in anhydrous toluene (3 mL) was treated with rhodium (II) acetate dimer (5 mg, 0.011 mmoL, 2.8 mol %) and warmed to 80° C. for 5 h. The reaction was concentrated, and purified via flash column chromatography (25-75% ethyl acetate in dichloromethane) to afford (2R,3R,4R,5R)-2-(((1-amino-3-ethoxy-1,3-dioxopropan-2-yl)oxy)methyl)-5-(2,6-dichloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate (101 mg, 45% in ˜85:15 mixture of diastereomers) as a colorless glass.

Step 4:

While under nitrogen, a solution of (2R,3R,4R,5R)-2-(((1-amino-3-ethoxy-1,3-dioxo-propan-2-yl)oxy)methyl)-5-(2,6-dichloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate (157 mg, 0.28 mmol) in dioxane (2.5 mL) was treated with diisopropylethyl-amine (0.100 mL, 0.61 mmoL, 2.2 eq) and cyclopentylamine (0.065 mL, 0.066 mmoL, 2.33 eq). After stirring at room temperature for 18 h, the mixture was diluted with ethyl acetate (20 mL), washed with water (10 mL), dried (Na₂SO₄), filtered, and concentrated to provide crude (2R,3R,4R,5R)-2-(((1-amino-3-ethoxy-1,3-dioxopropan-2-yl)oxy)methyl)-5-(2-chloro-6-(cyclopentylamino)-9H-purin-9-yl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate.

Step 5:

The resulting residue from the previous step was stirred in ammonium hydroxide and ethanol (1:1/v:v, 10 mL) at room temperature overnight. The mixture was concentrated, dissolved in THF (2.5 mL) and treated with lithium hydroxide (23 mg, 0.96 mmoL, 3.4 eq) dissolved in water (2.5 mL). The mixture was stirred at room temperature with occasional gentle heating for ˜3 h, then neutralized with TN HCl to pH-6 and concentrated in vacuo. The crude product was dissolved in water and purified by reverse phase HPLC and dried by lyophilization to provide the title compound (52 mg, 37% for 3 steps) as a voluminous white solid.

¹H NMR (400 MHz, D₂O) of major isomer: δ 8.30 (s, 1H), 5.81 (m, 1H), 4.88 (d, J=6.6 Hz, 1H), 4.80 (d, J=6.8 Hz, 1H), 4.24 (m, 2H), 4.20 (bs, 1H), 3.83 (m, 2H), 3.01 (s, 1H), 1.85 (m, 2H), 1.49 (m, 6H). 1H NMR (400 MHz, D₂O) of minor isomer: δ 8.39 (s, 1H), 5.81 (m, 1H), 4.88 (d, J=6.6 Hz, 1H), 4.80 (d, J=6.8 Hz, 1H), 4.24 (m, 2H), 4.20 (bs, 1H), 3.83 (m, 2H), 2.99 (s, 1H), 1.85 (m, 2H), 1.49 (m, 6H). HPLC: Rt=7.08 min, 93.0%. ESI-MS for C₂₀H₂₃ClN₆O₇ calcd. 494.13, found 493.2 (M−); ESI-MS for C₁₀H₁₁ClN₅ calcd. 236.07, found 236.0 (M-ribose fragment).

Example 116 Synthesis of 2-(((2R,3S,4R,5R)-5-(2-chloro-6-(cyclopentylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonamide

The title compound was prepared as a second product from step 5 in the synthesis of example 115. It was isolated as a voluminous white solid (8.5 mg, 6%).

¹H NMR (400 MHz, DMSO-d₆): 8.57 (s, 0.5H), 8.31 (s, 1H), 7.73 (s, 1H), 7.38 (m, 1.5H), 7.21 (m, 1.5H), 7.05 (m, 0.5H), 6.87 (m, 0.5H), 6.20 (m, 1H), 6.02 (d, J=7.0 Hz, 1H), 5.79 (d, J=7.8 Hz, 1H), 5.02 (s, 1H), 4.73 (s, 1H), 4.39 (m, 1H), 4.18 (m, 1H), 3.79 (m, 1H), 3.68 (s, 1H), 1.85 (m, 2H), 1.49 (m, 6H). HPLC: Rt=6.64 min, 97.1%. ESI-MS for C₂₀H₂₄ClN₇O₆ calcd. 493.15, found 492.3 (M−); ESI-MS for C₁₀H₁₁ClN₅ calcd. 236.1, found 236.1 (M-ribose fragment).

Example 117 Synthesis of 2-(((2R,3S,4R,5R)-5-(2-chloro-6-(methylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except methylamine was used in place of benzylamine in step 7 and step 4 is eliminated.

¹H NMR (400 MHz, CD₃OD) δ 8.88 (s, 1H), 6.05 (d, J=7.6 Hz, 1H), 5.03 (d, J=7.6 Hz, 1H), 4.62 (s, 1H), 4.26 (m, 1H), 4.04 (m, 1H), 3.90 (m, 1H), 3.11 (s, 1H), 3.07 (s, 3H). HPLC: Rt=5.92 min, 97.9%. ESI-MS for C₁₆H₁₆ClN₅O₈ calcd. 441.07, found 442.5 (M+); ESI-MS for C₆H₅ClN₅ calcd. 182.02, found 184.2 (M-ribose fragment).

Example 118 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-(benzylamino)-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

The title compound was prepared in a manner analogous to that set forth in Example 59, except step 4 was eliminated.

¹H NMR (400 MHz, CD₃OD) δ 8.87 (s, 1H), 7.39 (m, 2H), 7.33 (m, 2H), 7.26 (m, 1H), 6.06 (d, J=7.6 Hz, 1H), 5.02 (d, J=7.6 Hz, 1H), 4.76 (m, 2H), 4.62 (s, 1H), 4.26 (s, 1H), 4.03 (m, 1H), 3.90 (m, 1H), 3.10 (s, 1H). HPLC: Rt=7.83 min, 98.2%. ESI-MS for C₂₂H₂₀ClN₅O₈ calcd. 517.10 found 516.7 (M−); ESI-MS for C₁₂H₉ClN₅ calcd. 258.05, found 258 (M-ribose fragment).

Example 119 Synthesis of 2-(((2R,3S,4R,5R)-5-(2-chloro-6-morpholino-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(phenylsulfonyl)acetic acid

The title compound was prepared in an analogous manner to Example 59 except ethyl 2-diazo-2-(phenylsulfonyl)acetate was used instead of 1-ethyl 3-(prop-1-en-1-yl) 2-diazomalonate in Step 3, morpholine was used in place of benzylamine in Step 7 and Step 4 is eliminated.

¹H NMR (400 MHz, DMSO-d₆) of major isomer: δ 8.40 (s, 1H), 7.83 (m, 2H), 7.66 (m, 2H), 7.53 (m, 1H), 5.83 (m, 1H), 5.50 (d, J=7.8 Hz, 1H), 4.80 (d, J=7.8 Hz, 1H), 4.16 (m, 4H), 3.98 (m, 1H), 3.76 (m, 4H), 3.63 (s, 1H). ¹H NMR (400 MHz, DMSO-d₆) of minor isomer: δ 8.41 (s, 1H), 7.83 (m, 2H), 7.66 (m, 2H), 7.53 (m, 1H), 5.83 (m, 1H), 5.50 (d, J=7.8 Hz, 1H), 4.66 (d, J=7.8 Hz, 1H), 4.16 (m, 4H), 3.98 (m, 1H), 3.76 (m, 4H), 3.61 (s, 1H). HPLC: Rt=7.83 (minor), 8.18 min (major), 99.6% (40:60). ESI-MS for C₂₆H₂₆ClN₅O₉ calcd. 587.14, found 588 (M+); ESI-MS for C₂₄H₂₄ClN₅O₉S calcd. 593.10, found 592 (M−); ESI-MS for C₂₃H₂₃ClN₅O₇S calcd. 548.10, found 548 (M-CO₂H); ESI-MS for C₉H₉ClN₅O calcd. 238.05, found 240 (M-ribose fragment).

Example 120 Synthesis of 2-(((2R,3S,4R,5R)-5-(2-chloro-6-(cyclopentylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(methylsulfonyl)acetic acid

The title compound was prepared in an analogous manner to Example 59 except ethyl 2-diazo-2-(methylsulfonyl)acetate was used instead of 1-ethyl 3-(prop-1-en-1-yl) 2-diazomalonate in Step 3, cyclopentanamine is used in place of benzylamine in Step 7 and Step 4 is eliminated.

¹H NMR (400 MHz, DMSO-d₆) of major isomer: δ 8.47 (s, 1H), 5.85 (m, 1H), 5.36 (m, 1H), 5.01 (m, 1H), 4.86 (d, J=8.0 Hz, 1H), 4.42 (m, 2H), 4.33 (m, 1H), 4.25 (m, 2H), 4.14 (m, 1H), 4.00 (m, 1H), 3.37 (s, 1H), 3.05 (s, 3H), 1.97 (m, 2H), 1.72 (m, 2H), 1.57 (m, 4H). ¹H NMR (400 MHz, DMSO-d₆) of minor isomer: δ 8.39 (s, 1H), 5.83 (m, 1H), 5.36 (m, 1H), 4.68 (d, J=8.0 Hz, 1H), 4.42 (m, 2H), 4.33 (m, 1H), 4.25 (m, 2H), 4.14 (m, 1H), 4.00 (m, 1H), 3.37 (s, 1H), 3.05 (s, 3H), 1.97 (m, 2H), 1.72 (m, 2H), 1.57 (m, 4H). HPLC: Rt=8.02 min, 98.4%. ESI-MS for C₂₀H₂₄ClN₅O₈S calcd. 529.10, found 530 (M+); ESI-MS for C₁₀H₁₁ClN₅ calcd. 236.07, found 238 (M-ribose fragment).

Examples 121 & 122 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-carbamoyl-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-benzyl-3-ethoxy-3-oxopropanoic acid and 2-(((2R,3S,4R,5R)-5-(6-amino-2-carbamoyl-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-benzylmalonic acid

Step 1:

To a solution of diethyl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-(N,N′-bis(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (1.00 g, 1.17 mmol, 1 eq) in DMSO (10 mL) and H₂O (2 mL) was added 1,4-diazabicyclo[2.2.2]octane (128 uL, 1.17 mmol, 1 eq) and NaCN (114.20 mg, 2.33 mmol, 2 eq). The solution was stirred at 60° C. for 3 h before it was diluted with water (15 mL) and extracted with ethyl acetate (3×15 mL). The combined organic layer was washed with water (50 mL), brine (50 mL), dried by Na₂SO₄, and filtered and concentrated. The crude residue was purified by Combi-flash (silica gel, 30-70% EtOAc in petroleum ether) to give diethyl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-(N,N′-bis(tert-butoxycarbonyl)-amino)-2-cyano-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (312 mg, 40% yield) as a yellow gum.

Step 2:

To a solution of diethyl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-(N,N′-bis(tert-butoxycarbonyl)amino)-2-cyano-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (50 mg, 75.23 umol, 1 eq) in DCM (1.7 mL) was added TFA (0.3 mL) at 0° C. The solution was stirred at 20° C. for 1 h before it was diluted with saturated aq. NaHCO₃ to adjust the pH to 9. The mixture was extracted with ethyl acetate (3×3 mL). The organic was concentrated to give crude diethyl 2-(((2R,3S,4R,5R)-5-(6-amino-2-cyano-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetra-hydrofuran-2-yl)methoxy)-2-benzylmalonate (45 mg) as a yellow gum.

Step 3:

To a solution of crude diethyl 2-(((2R,3S,4R,5R)-5-(6-amino-2-cyano-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetra-hydrofuran-2-yl)methoxy)-2-benzyl-malonate (65 mg, 115.14 umol, 1 eq) in MeCN (2 mL) was added 3,4,6,7,8,9-hexahydro-2H-pyrimido[1,2-a]-pyrimidine (TBD) (1 M aq., 461 uL, 4 eq). The reaction mixture was stirred at 20° C. for 18 h before it was concentrated. The crude residue was purified by preparative HPLC and the fractions were dried by lyophilization to give 2-(((2R,3S,4R,5R)-5-(6-amino-2-carbamoyl-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-benzyl-3-ethoxy-3-oxopropanoic acid (Example 121) (4.1 mg, 5% yield) as a white solid and 2-(((2R,3S,4R,5R)-5-(6-amino-2-carbamoyl-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-benzylmalonic acid (Example 122) (2.2 mg, 3% yield) as a white solid.

Example 121: ¹H NMR (400 MHz, CD₃OD) δ ppm 8.19-8.39 (m, 1H) 7.26 (br d, J=5.88 Hz, 2H) 7.03-7.12 (m, 3H) 6.20 (dd, J=9.69, 7.19 Hz, 1H) 4.91-4.97 (m, 1H) 4.29 (br s, 1H) 3.98-4.24 (m, 4H) 3.41-3.53 (m, 1H) 3.31-3.40 (m, 1H) 2.97-3.08 (m, 1H) 1.18 (q, J=7.25 Hz, 3H); LC/MS [M+H]=555.1.

Example 122: ¹H NMR (400 MHz, CD₃OD) δ ppm 8.504 (s, 1H) 7.16-7.28 (m, 2H) 7.07 (br s, 3H) 6.20 (d, J=5.88 Hz, 1H) 4.92-4.99 (m, 1H) 4.37 (br s, 1H) 3.97 (br d, J=3.63 Hz, 2H) 3.32-3.48 (m, 2H) 3.01 (s, 1H); LC/MS [M+H]=527.0.

Example 123 Synthesis of (1-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-methoxy-2-oxoethyl)phosphonic acid

Step 1:

A mixture of (2R,3R,4R,5R)-5-(6-(N,N′-bis(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyl-2-(hydroxymethyl)tetrahydrofuran-3,4-diyl diacetate (565 mg, 0.926 mmol, 1.0 eq) and methyl 2-diazo-2-(dimethoxyphosphoryl)acetate (247 mg, 1.20 mmol, 1.3 eq) was azeotroped twice with toluene and the resulting oil was re-dissolved in toluene (5.7 mL). The reaction solution was stirred at ambient temperature under argon atmosphere and fitted with a jacketed reflux condenser. Rhodium(II) acetate (0.185 mmol, 82 mg, 0.2 eq) was added and the reaction heated at 75° C. for 9 h before it was cooled to room temperature. The reaction mixture was concentrated and the resulting oil was purified by flash silica gel column chromatography to provide (2R,3R,4R,5R)-5-(6-(N,N′-bis(tert-butoxy-carbonyl)acetamido)-2-chloro-9H-purin-9-yl)-2-((1-(dimethoxyphosphoryl)-2-methoxy-2-oxoethoxy)methyl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate.

Steps 2-3:

Deprotection of the product from the previous step was performed according to the procedure described for step 4 in Example 121. Aq. NaOH solution was used instead of KOEt that lead to the carboxylic acid. The title compound was isolated as a white solid from preparative reversed-phase HPLC.

¹H NMR (CD₃OD, 300 MHz) δ 8.08 (s, 1H), 6.06 (bs, 1H), 5.06-5.08 (d, J=5 Hz, 1H), 4.28 (s, 1H), 3.90-4.10 (m, 2H), 3.79 (s, 3H), 3.98 (bs, 2H), 3.13 (s, 1H); LC/MS [M+H]=478.2.

Example 124 Synthesis of (1-(((2R,3S,4R,5R)-5-(2-chloro-6-morpholino-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-ethoxy-2-oxoethyl)phosphonic acid

(1-(((2R,3S,4R,5R)-5-(2-chloro-6-morpholino-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-ethoxy-2-oxoethyl)phosphonic acid is prepared in a manner analogous to that set forth in Example 59, except ethyl 2-diazo-2-(diethoxyphos-phoryl)acetate in place of 2-diazomalonate in step 3, morpholine is used in place of benzylamine in step 7 and step 4 is eliminated. Compound was isolated as a 1:1 mixture of diastereomers.

¹H NMR (400 MHz, DMSO-d₆) of major isomer: δ 8.59 (s, 1H), 5.90 (m, 1H) 5.00 (d, J=7.0 Hz, 1H), 4.25 (m, 2H), 4.05 (m, 4H), 3.99 (m, 1H), 3.83 (m, 1H), 3.75 (m, 4H), 3.01 (s, 1H) 1.05 (t, J=7.1 Hz, 3H). 1H NMR (400 MHz, DMSO-d₆) of minor isomer: δ 8.48 (s, 1H), 5.88 (m, 1H), 4.94 (d, J=6.9 Hz, 1H), 4.25 (m, 2H), 4.05 (m, 4H), 3.99 (m, 1H), 3.83 (m, 1H), 3.75 (m, 4H), 3.01 (s, 1H), 0.99 (t, J=7.1 Hz, 3H). HPLC: minor isomer=6.63 min; major isomer=6.65 min, 98.6%. LC-MS: m/z=562 (M+); m/z=240 (M-ribose fragment).

Example 125 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-3-ethynyl-3,4-dihydroxy-5-(5-(trifluoromethyl)-3H-imidazo[4,5-b]pyridin-3-yl)tetrahydrofuran-2-yl)methoxy)malonic acid

Proceeding as described in Example 15 above but substituting 6-amino-2-chloroadenine with 5-(trifluoromethyl)-3H-imidazo[4,5-b]pyridine provided the title compound as a white solid.

¹H NMR (CD₃OD, 300 MHz) δ 8.82 (bs, 1H), 8.23 (d, J=8 Hz, 1H), 7.78 (d, J=8 Hz, 1H), 7.29-7.26 (m, 2H), 7.03-7.00 (m, 3H), 6.32 (d, J=7 Hz, 1H), 5.10 (d, J=7 Hz, 1H), 4.37-4.36 (m, 1H), 4.08 (d, J=3 Hz, 2H), 3.42 (dd, J=15, 28 Hz, 2H), 2.98 (s, 1H); LC/MS [M+H]=535.2.

Example 126 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(thiazol-4-ylmethyl)malonic acid

Proceeding as described in Example 15 above but substituting allyl bromide with 4-(chloromethyl)thiazole provided the title compound as a white solid.

¹H NMR (CD₃OD, 300 MHz) δ 8.76 (bs, 1H), 8.57 (bs, 1H), 7.36 (bs, 1H), 6.00 (d, J=7 Hz, 1H), 5.00-4.95 (m, 1H), 4.35 (bs, 1H), 4.08-4.04 (m, 2H), 3.66-3.64 (m, 2H), 2.98 (s, 1H); LC/MS [M+H]=524.9.

Example 127 Synthesis of 2-(((2R,3S,4R,5R)-5-(2-acetyl-6-amino-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-benzylmalonic acid

Step 1:

To a suspension of 6-amino-2-chloroadenine (3.0 g, 17.69 mmol, 1 eq) in DCM (60 mL) was added 4-DMAP (2.16 g, 17.69 mmol, 1 eq), TEA (21.48 g, 212.30 mmol, 29.55 mL, 12 eq) and (Boc)₂O (30.89 g, 141.53 mmol, 8 eq). The suspension was stirred at 20° C. for 18 h before it was diluted with saturated aq. NH₄Cl (100 mL), and extracted with ethyl acetate (2×100 mL). The combined organic layer was washed with brine (200 mL), dried by Na₂SO₄, filtered and concentrated. The crude residue was purified by Combi-flash (silica gel, 0-20% EtOAc in petroleum ether) to give tert-butyl 6-(N,N′-bis(tert-butoxycarbonyl)amino)-2-chloro-9H-purine-9-carboxylate (904 mg, 11% yield) as a yellow gum.

Step 2:

To a solution of tert-butyl 6-(N,N′-bis(tert-butoxycarbonyl)amino)-2-chloro-9H-purine-9-carboxylate (900 mg, 1.92 mmol, 1 eq) in DMF (12 mL) was added Pd(PPh₃)₂Cl₂ (134.43 mg, 191.52 umol, 0.1 eq) and tributyl(1-ethoxyvinyl)stannane (832 uL, 2.46 mmol, 1.29 eq) under N₂ atmosphere. The suspension was stirred at 95° C. for 3 h before it was diluted with saturated aq. KF solution (8 mL) and stirred at 20° C. for 1 h. The mixture was extracted with ethyl acetate (2×8 mL). The combined organic layer was washed with water (20 mL), brine (15 mL), dried by Na₂SO₄, filtered and concentrated. The crude residue was purified by Combi-flash (silica gel, 30-70% EtOAc in petroleum ether) to give tert-butyl N-(tert-butoxycarbonyl)amino-(2-(1-ethoxyvinyl)-9H-purin-6-yl)carbamate (256 mg, 33% yield) as a white solid.

Step 3:

To a solution of the product from the last step (60 mg, 109.38 umol, 1 eq) and diethyl 2-benzyl-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-ethynyltetrahydrofuran-2-yl)methoxy)-malonate (53.22 mg, 131.26 umol, 1.2 eq) in MeCN (1 mL) was added BSA (65 uL, 262.52 umol, 2.4 eq). The solution was stirred at 65° C. for 0.5 h before it was cooled to 25° C. and followed by addition of TMSOTf (24 uL, 131.26 umol, 1.2 eq). The resulting solution was stirred at 65° C. for 1 h before it was diluted with saturated aq. NaHCO₃ (5 mL) and extracted with EtOAc (2×5 mL). The combined organic layer was concentrated. The crude residue was purified by preparative TLC (EtOAc) to give diethyl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-amino-2-(1-ethoxyvinyl)-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)-methoxy)malonate (42 mg, 55% yield) as a colorless gum.

Step 4:

To a solution of diethyl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-amino-2-(1-ethoxyvinyl)-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-malonate (40 mg, 57.66 umol, 1 eq) in THF (1.5 mL) was added 1M aq. HCl aq. (0.5 mL, 8.67 eq). The mixture was stirred at 20° C. for 21 before it was diluted with saturated aq. NaHCO₃ (5 mL) and the mixture was extracted with ethyl acetate (3×5 mL). The combined organic layer was dried by Na₂SO₄, filtered and concentrated to provide crude diethyl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(2-acetyl-6-amino-9H-purin-9-yl)-3-ethynyltetrahydro-furan-2-yl)methoxy)malonate (40 mg) as a light yellow gum.

Step 5:

To a solution of crude diethyl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(2-acetyl-6-amino-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (30 mg, 45.07 umol, 1 eq) in THF (4 mL) was added 1M aq. LiOH aq. (901 uL, 20 eq). The mixture was stirred at 20° C. for 6 before it was acidified with 1N aq. HCl to pH 6 and concentrated. The crude residue was purified by preparative HPLC and the fraction was dried by lyophilization to give the title compound (1.4 mg, 6% yield) as a white solid.

¹H NMR (CD₃OD, 300 MHz) δ 8.43 (bs, 1H), 7.14-6.98 (m, 5H), 6.06 (d, J=6.4 Hz, 1H), 4.89 (d, J=6.8 Hz, 1H), 4.26 (m, 1H), 3.94-3.91 (m, 2H), 3.30-3.21 (m, 2H), 2.91 (s, 1H), 2.61 (s, 3H); LC/MS [M+H]=526.0.

Example 128 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(thiophen-2-ylmethyl)malonic acid

Proceeding as described in Example 15 above but substituting allyl bromide with 2-(bromomethyl)thiophene provided the title compound as a white solid.

¹H NMR (CD₃OD, 300 MHz) δ 8.37 (bs, 1H), 7.10 (d, J=5 Hz, 1H), 6.93-6.72 (m, 2H), 6.00 (d, J=7.2 Hz, 1H), 4.98 (d, J=7.6 Hz, 1H), 4.23 (bs, 1H), 4.06 (bs, 2H), 3.62-3.58 (m, 2H), 2.94 (s, 1H); LC/MS [M+H]=523.9.

Example 129 Synthesis of 2-(((2R,3S,4R,5R)-5-(2-chloro-6-(cyclopentylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(phenylsulfonyl)acetic acid

The title compound was prepared in an analogous manner to Example 59 except ethyl 2-diazo-2-(phenylsulfonyl)acetate was used instead of 1-ethyl 3-(prop-1-en-1-yl) 2-diazo malonate in Step 3, cyclopentanamine is used in place of benzylamine in Step 7 and Step 4 is eliminated.

LC/MS [M+H]=592.0.

Example 130 Synthesis of 2-(((2R,3S,4R,5R)-5-(2-chloro-6-(methylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(1-ethyl-2-oxo-1,2-dihydropyridin-3-yl)benzyl)malonic acid

Proceeding as described in Example 20 above but substituting diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-N,N′-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate with diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-((tert-butoxycarbonyl)(methyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyl-tetrahydrofuran-2-yl)methoxy)malonate provided the title compound as a white solid.

¹H NMR (400 MHz, CD₃OD) δ ppm 8.04 (s, 1H), 7.58 (dd, J=6.7, 1.9 Hz, 1H), 7.27-7.38 (m, 5H), 6.35 (t, J=6.9 Hz, 1H), 5.95 (d, J=7.8 Hz, 1H), 4.77 (d, J=7.8 Hz, 1H), 4.28 (t, J=2.6 Hz, 1H), 3.96-4.13 (m, 4H), 3.38-3.57 (m, 2H), 3.05 (s, 1H) 2.99 (m, 3H), 1.32 (t, J=7.3 Hz, 3H); LC/MS [M+H]=653.1.

Example 131 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-chloro-3-methyl-1H-pyrazolo[3,4-b]pyridin-1-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)malonic acid

Step 1:

To a solution of (4-aminophenyl)methanol (27.65 g, 224.44 mmol, 1 eq) in a mixture of anhydrous DCM (100 mL) and anhydrous THF (50 mL) maintained at 25° C. was added 1-chloro-3-isocyanatopropane (26.83 g, 224.44 mmol, 1 eq) dropwise. The reaction mixture became slightly exothermic and turned yellow as a precipitate was formed within 15 minutes. The mixture was stirred for 1.5 h before hexanes (50 mL) was added. The mixture was stirred for additional 15 min before the solid product was collected by filtration, rinsing with a mixture of DCM and hexanes (5:1=v:v). Upon drying provided 1-(3-chloropropyl)-3-(4-(hydroxymethyl)phenyl)urea (38.45 g) as a light yellow solid.

Step 2:

To a solution of 1-(3-chloropropyl)-3-(4-(hydroxymethyl)phenyl)urea (30.00 g, 123.6 mmol, 1.0 eq) in THF (300 mL) at 25° C. was added a solution of 1M t-BuOK in THF (247.2 mL, 247.2 mmol, 2.0 eq) dropwise while stirring vigorously with a mechanical stirrer. The resulting heterogeneous mixture was stirred at 25° C. for 6 h before it was cooled to 0° C. and acidified to pH 5-6 with 2N aq. HCl. The organic volatile was then removed under reduced pressure. The crude solid was taken up in MeOH (75 mL) and concentrated. The resulting solid mixture was rinsed with a solution of 7% MeOH in DCM (220 mL) under gentle heating and the solid was filtered off. The solid was rinsed again with 7% MeOH in DCM (150 mL) and filtered. The combined rinse was concentrated to give the desired crude 1-(4-(hydroxymethyl)phenyl)tetrahydropyrimidin-2 (1H)-one as a yellowish solid (27.68 g).

Step 3:

To a suspension of crude 1-(4-(hydroxymethyl)phenyl)tetrahydropyrimidin-2 (1H)-one (15.00 g, 72.74 mmol, 1 eq) in DCM (250 mL) was added a solution of thionyl chloride (10.61 mL, 145.48 mmol, 2 eq) at 25° C. under a N₂ atmosphere. The mixture was stirred at 25° C. for 8 h before it was diluted with EtOAc (250 mL) and stirred for 30 min. The solid was collected by filtration, rinsed with EtOAc and dried to provide crude 1-(4-(chloro-methyl)phenyl)tetrahydropyrimidin-2 (1H)-one (15.00 g).

Step 4:

To a solution of diethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-2,2-dimethyl-6-(prop-1-yn-1-yl)tetrahydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)malonate (7.04 g, 16.99 mmol, 1 eq) in DMF (70 mL) was added Cs₂CO₃ (11.07 g, 33.98 mmol, 2 eq) and crude 1-(4-(chloro-methyl)phenyl)tetrahydropyrimidin-2 (1H)-one (5.09 g, 25.49 mmol, 1.5 eq) at 20° C. The mixture was stirred at 20° C. for 5 h before it was diluted with H₂O (300 mL) and extracted with EtOAc (3×100 mL). The combined organic layer was washed with brine (200 mL), dried over Na₂SO₄, filtered and concentrated. The crude product was purified by flash silica gel column chromatography (10-40% acetone in DCM) to provide diethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-6-ethynyl-2,2-dimethyltetrahydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)-2-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)malonate (9.62 g, 94% yield) as a solid.

Step 5:

To a solution of diethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-6-ethynyl-2,2-dimethyl-tetrahydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)-2-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)malonate (17.31 g, 28.72 mmol, 1 eq) in DCM (90 mL) was added H₂O (18 mL) and TFA (90 mL, 1.22 mol, 42 eq) at 0° C. The reaction mixture was stirred at 20-25° C. for 16 h before it was concentrated under reduced pressure. The residue was azeotroped with DCM (2×50 mL) under reduced pressure to provide the crude product diethyl 2-(((2R,3S,4R)-3-acetoxy-3-ethynyl-4,5-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)malonate which was used in the next step without further purification.

Step 6:

To a solution of crude diethyl 2-(((2R,3S,4R)-3-acetoxy-3-ethynyl-4,5-dihydroxy-tetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)malonate (17.23 g, crude) in DCM (170 mL) was added 4-DMAP (374 mg, 3.06 mmol, 0.1 eq), Ac₂O (17.21 mL, 183.77 mmol, 6 eq) and pyridine (19.78 mL, 245.02 mmol, 8 eq) at 0° C. The reaction mixture was stirred at 20-25° C. for 16 h before it was concentrated under reduced pressure. The residue was re-dissolved in EtOAc (200 mL), washed with 1N aq. HCl (150 mL), 10% aq. Cu₂SO₄ (150 mL), saturated aq. NaHCO₃ (150 mL) and brine (150 mL), dried over Na₂SO₄, filtered and concentrated to provide crude diethyl 2-(4-(2-oxotetrahydro-pyrimidin-1 (2H)-yl)benzyl)-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (19.24 g) as a foam which was carried onto the next step without further purification.

Step 7:

To a suspension of crude diethyl 2-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (450 mg, 0.70 mmol, 1 eq) and 6-chloro-3-methyl-1H-pyrazolo[3,4-b]pyridine (128 mg, 0.77 mmol, 1.1 eq) in MeCN (4 mL) was added DBU (315 uL, 2.09 mmol, 3.0 eq) at 0° C. The solution was stirred at 0° C. for 5 min and followed by addition of a solution of TMSOTf (566 uL, 3.13 mmol, 4.5 eq) in MeCN (2 mL) dropwise. The solution was stirred at 0° C. for 0.5 h and then stirred at 70° C. for 16 h before it was allowed to cool to 25° C. and adjusted the pH to 9 with saturated aq. NaHCO₃. The mixture was extracted with ethyl acetate (2×40 mL). The combined organic layer was dried with Na₂SO₄, filtered and concentrated. The crude residue which was purified by Combi-flash on silica gel (0-10% MeOH in DCM) to give diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-chloro-3-methyl-1H-pyrazolo[3,4-b]pyridin-1-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)-malonate (255 mg, 49% yield) as a yellow gum.

Step 8:

To a solution of diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-chloro-3-methyl-1H-pyrazolo[3,4-b]pyridin-1-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxotetrahydro-pyrimidin-1 (2H)-yl)benzyl)malonate (296 mg, 392 umol, 1 eq) in THF (6 mL) was added aq. LiOH solution (2 M, 1.96 mL, 10 eq). The solution was stirred at 50° C. for 2 h before the organic volatile was removed under reduced pressure. To the water layer was added 1N HCl to adjust the pH to 5-6. The mixture was concentrated to give crude product which was purified by preparative HPLC (Column: YMC-Actus Triart C18 150*30 mm*5 um; mobile phase: [water (0.225% FA)-ACN]; B %: 25%-45%, 10 min). The product was isolated by lyophilization to give 2-(((2R,3S,4R,5R)-5-(6-chloro-3-methyl-1H-pyrazolo[3,4-b]pyridin-1-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)malonic acid (32 mg) as a white solid.

¹H NMR (400 MHz, DMSO-d₆) δ ppm 8.27 (d, J=8.28 Hz, 1H), 7.31 (d, J=8.28 Hz, 1H), 6.97 (d, J=8.53 Hz, 2H), 6.81 (d, J=8.53 Hz, 2H), 6.49 (s, 1H), 6.20 (s, 1H), 6.13 (d, J=7.53 Hz, 1H), 5.97 (s, 1H), 4.98 (d, J=7.53 Hz, 1H), 4.13 (dd, J=8.41, 2.64 Hz, 1H), 3.93-3.99 (m, 1H), 3.84-3.91 (m, 1H), 3.64 (s, 1H), 3.42-3.52 (t, J=5.60 Hz, 2H), 3.17-3.23 (m, 2H), 3.05-3.16 (m, 2H), 2.45 (s, 3H), 1.90 (m, 2H); LC/MS [M+H]=614.3.

Example 132 Synthesis of 2-(((2R,3S,4R,5R)-5-(2-chloro-6-oxo-1H-purin-9 (6H)-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)malonic acid

Step 1:

To a solution of 2,6-dichloro-9H-purine (379.97 mg, 2.01 mmol) in MeCN (5 mL) was added BSA (956 uL, 3.87 mmol) at 25° C. The reaction mixture was stirred at 65° C. for 0.5 h and then cooled back to 25° C. To this mixture was added diethyl 2-(4-(2-oxotetra-hydropyrimidin-1 (2H)-yl)benzyl)-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (1 g) in MeCN (5 mL) and TMSOTf (419 uL, 2.32 mmol) at 25° C. and further stirred at 65° C. for 5 h. The reaction mixture was allowed to cool to 25° C. before it was quenched with saturated aq. NaHCO₃ (10 mL) and extracted with EtOAc (3×5 mL). The combined organic layer was washed brine (10 mL), dried over anhydrous Na₂SO₄, filtered and concentrated. The crude residue was purified by flash silica gel column chromatography (0-10% MeOH in DCM) to provide diethyl 2-(((2R,3R,4R,5R)-3,4-di-acetoxy-5-(2,6-dichloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)malonate (365 mg) as a foam.

Step 2:

To a solution of diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(2,6-dichloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)malonate (180 mg) in THF (2 mL) was added LiOH·H₂O (97.39 mg, 2.32 mmol, 10 eq) in H₂O (1 mL) at 25° C. The reaction mixture was stirred at 40° C. for 2 h before the organic volatile was removed under reduced pressure. The aqueous phase was acidified to pH 5-6 with 1N aq. HCl and concentrated under reduced pressure. The crude residue was purified by preparative HPLC (column: YMC-Actus Triart C18 150*30 mm*5 um; mobile phase: [water (0.225% FA)-ACN]; B %: 13%-33%, 10 min) and dried by lyophilization to provide 2-(((2R,3S,4R,5R)-5-(2-chloro-6-oxo-1H-purin-9 (6H)-yl)-3-ethynyl-3,4-dihydroxy-tetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)malonic acid (15 mg) as a white solid. 1H NMR (400 MHz, CD₃OD) δ ppm 8.62 (s, 1H), 7.24 (d, J=8.31 Hz, 2H), 7.03 (d, J=8.31 Hz, 2H), 6.32 (d, J=6.48 Hz, 1H), 4.61 (d, J=6.48 Hz, 1H), 4.28-4.34 (m, 1H), 3.92-4.04 (m, 2H), 3.55-3.66 (m, 2H), 3.33-3.40 (m, 4H), 3.02 (s, 1H), 1.99-2.06 (m, 2H); LC/MS [M+H]=617.2.

Example 133 Synthesis of 2-(((2R,3S,4R,5R)-3-ethynyl-3,4-dihydroxy-5-(5-methyl-2,4-dioxo-3,4-dihydropyrimidin-1 (2H)-yl)tetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)malonic acid

Step 1:

To the mixture of 5-methylpyrimidine-2,4(1H,3H)-dione (100 mg, 792.94 umol, 1 eq) in MeCN (2 mL) was added BSA (490 uL, 1.98 mmol, 2.5 eq). The mixture was stirred at 85° C. for 0.5 h. The mixture was cooled to 0° C. and followed by addition of a solution of diethyl 2-(4-(2-oxotetra-hydropyrimidin-1 (2H)-yl)benzyl)-2-(((2R,3R,4R)-3,4,5-triace-toxy-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (385 mg) in MeCN (2 mL) and TMSOTf (430 uL, 2.38 mmol, 3.0 eq) was added dropwise. The mixture was stirred at 65° C. under N₂ atmosphere for 5 h before it was allowed to cool to 25° C. and quenched with saturated aq. NaHCO₃ (10 mL). The mixture was extracted with EtOAc (3×5 mL). The organic layers were combined, dried over Na₂SO₄, filtered and concentrated in vacuo. The crude compound was purified by silica gel column chromatography (0-5% MeOH in DCM) to provide diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-3-ethynyl-5-(5-methyl-2,4-dioxo-3,4-dihydropyrimidin-1 (2H)-yl)tetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)malonate (208 mg, 37% yield) as a solid.

Step 2:

To a solution of diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-3-ethynyl-5-(5-methyl-2,4-dioxo-3,4-dihydropyrimidin-1 (2H)-yl)tetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxotetrahydro-pyrimidin-1 (2H)-yl)benzyl)malonate (200 mg, 280.62 umol, 1 eq) in THF (2 mL) was added LiOH·H₂O (58.88 mg, 1.40 mmol, 5 eq) in H₂O (1 mL) at 20-25° C. The reaction mixture was stirred at 40° C. for 1 h before the organic volatile was removed under reduced pressure. The aqueous phase was acidified to pH is 5-6 with 1N aq. HCl and concentrated under reduced pressure. The crude residue was purified by preparative HPLC (column: YMC-Actus Triart C18 150*30 mm*5 um; mobile phase: [water (0.225% FA)-ACN]; B %: 13%-33%, 10 min) and then followed by lyophilization to provide 2-(((2R,3S,4R,5R)-3-ethynyl-3,4-dihydroxy-5-(5-methyl-2,4-dioxo-3,4-dihydropyrimidin-1 (2H)-yl)tetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)malonic acid (49 mg) as a white solid.

¹H NMR (400 MHz, CD₃OD) δ ppm 7.83 (d, J=0.75 Hz, 1H), 7.33 (d, J=8.28 Hz, 2H), 7.11 (d, J=8.28 Hz, 2H), 6.06 (d, J=7.78 Hz, 1H), 4.44 (d, J=7.78 Hz, 1H), 4.16 (t, J=2.26 Hz, 1H), 3.92-4.05 (m, 2H), 3.47-3.65 (m, 3H), 3.33-3.41 (m, 3H), 2.98 (s, 1H), 2.04 (m, 2H), 1.62 (s, 3H); LC/MS [M+H]=573.1.

Example 134 Synthesis of 2-(((2R,3S,4R,5R)-5-(2,4-dioxo-3,4-dihydropyrimidin-1 (2H)-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)malonic acid

Proceeding as described in Example 133 above but substituting thymine with uracil provided the title compound as a white solid.

¹H NMR (400 MHz, CD₃OD) δ ppm 7.91 (d, J=8.0 Hz, 1H), 7.31 (d, J=8.4 Hz, 2H), 7.15 (d, J=8.4 Hz, 2H), 6.01 (d, J=7.5 Hz, 1H), 5.20 (d, J=8.0 Hz, 1H), 4.36 (d, J=7.5 Hz, 1H), 4.17 (t, J=2.4 Hz, 1H), 3.99 (dd, J=18.8, 2.5 Hz, 2H), 3.55-3.66 (m, 2H), 3.44-3.52 (m, 1H), 3.33-3.38 (m, 3H), 3.01 (s, 1H), 1.99-2.10 (m, 2H); LC/MS [M+H]=559.1.

Example 135 Synthesis of 2-(((2R,3S,4R,5R)-5-(4-amino-2-oxopyrimidin-1 (2H)-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)malonic acid

Proceeding as described in Example 133 above but substituting thymine with cytosine provided the title compound as a white solid.

¹H NMR (400 MHz, DMSO-d₆) δ ppm 7.92-8.05 (m, 1H), 7.76-7.92 (br s, 1H), 7.45-7.62 (s, 1H), 7.03-7.19 (m, 4H), 6.55 (s, 1H), 5.91-5.99 (m, 1H), 5.87 (d, J=6.80 Hz, 1H), 5.80 (d, J=6.00 Hz, 1H), 5.57 (d, J=7.20 Hz, 1H), 4.13 (t, J=6.80 Hz, 1H), 4.02-4.08 (m, 1H), 3.68-3.82 (m, 2H), 3.50-3.57 (m, 2H), 3.22 (s, 1H), 3.19-3.22 (m, 3H), 1.82-1.99 (m, 2H); LC/MS [M+H]=558.3.

Example 136 Synthesis of 2-(((2R,3S,4R,5R)-5-(2-chloro-6-((cyclopropylmethyl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)malonic acid

Proceeding as described in Example 133 above but substituting thymine with 2-chloro-N-(cyclopropylmethyl)-9H-purin-6-amine provided the title compound as a white solid.

¹H NMR (400 MHz, CD₃OD) δ ppm 8.22 (s, 1H), 7.28 (br d, J=8.03 Hz, 2H), 7.03 (d, J=8.28 Hz, 2H), 5.97 (d, J=7.28 Hz, 1H), 4.72-4.77 (m, 1H), 4.28 (s, 1H), 3.95-4.05 (m, 2H), 3.34-3.52 (m, 8H), 3.05 (s, 1H), 1.92-2.02 (m, 2H), 1.11-1.20 (m, 1H), 0.51-0.59 (m, 2H), 0.34 (q, J=4.85 Hz, 2H); LC/MS [M+H]=670.1.

Example 137 Synthesis of 2-(((2R,3S,4R,5R)-5-(2-chloro-6-(methylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(3-(2-hydroxyethyl)-2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)malonic acid

Step 1:

To a solution of compound 1-(3-chloropropyl)-3-(4-(hydroxymethyl)phenyl)urea (5 g, 20.60 mmol, 1 eq) in THF (100 mL) at 0° C. was added NaH (9.89 g, 247.22 mmol, 60% in mineral oil, 12 eq). The reaction mixture was stirred at 25° C. for 1.5 h before it was then added TBDPSCl (6.80 g, 24.72 mmol, 1.2 eq) and stirred further for additional 1.5 h. To the reaction mixture was then added allyl bromide (9.97 g, 82.41 mmol, 4 eq) and stirred further for 16 h. To the reaction mixture was added H₂O (50 mL) and the resulting mixture was extracted with EtOAc (3×100 mL). The combined organic layer was washed with brine (100 mL), dried over Na₂SO₄, filtered and concentrated. The crude residue was purified by silica gel column chromatography and eluted with EtOAc in petroleum ether (0-30%) to provide 1-allyl-3-(4-(((tert-butyldiphenylsilyl)oxy)methyl)phenyl)tetrahydropyrimidin-2 (1H)-one (6 g, 60% yield) as an oil.

Step 2:

To a solution of compound 1-allyl-3-(4-(((tert-butyldiphenylsilyl)oxy)methyl)-phenyl)tetrahydropyrimidin-2 (1H)-one (6 g, 12.38 mmol, 1 eq) in a mixture of MeOH (60 mL) and DCM (30 mL) at −78° C., ozone (15 psi) was introduced until the blue color of the solution persisted for 20 minutes. The excess of ozone was removed by bubbling nitrogen gas for 10 minutes. To this reaction mixture was added NaBH₄ (937 mg, 24.76 mmol, 2 eq) and the mixture was allowed to reach 0° C. and stirred for 15 h at 25° C. The mixture was poured into 1N aq. HCl (50 mL) and extracted with EtOAc (2×100 mL). The combined organic layer was washed with water (100 mL) and brine (100 mL), dried (Na₂SO₄), filtered and concentrated to give crude 1-(4-(((tert-butyldiphenylsilyl)oxy)methyl)phenyl)-3-(2-hydroxyethyl)tetrahydropyrimidin-2 (1H)-one (6.6 g) as an oil which was used directly in the next step.

Step 3:

To a solution of crude 1-(4-(((tert-butyldiphenylsilyl)oxy)methyl)phenyl)-3-(2-hydroxyethyl)tetrahydropyrimidin-2 (1H)-one (12.38 mmol, 1 eq) in DCM (40 mL) and pyridine (3.00 mL, 37.14 mmol, 3 eq) at 25° C. was added Ac₂O (2.32 mL, 24.76 mmol, 2 eq) and 4-DMAP (151 mg, 1.24 mmol, 0.1 eq). The mixture was stirred for 2 h before it was quenched with H₂O (60 mL). The mixture was extracted with EtOAc (3×50 mL). The combined organic layer was washed with water (2×30 mL), brine (30 mL), dried over Na₂SO₄, filtered and concentrated to provide the crude 2-(3-(4-(((tert-butyldiphenylsilyl)-oxy)methyl)phenyl)-2-oxotetrahydropyrimidin-1 (2H)-yl)ethyl acetate which was used in the next step directly.

Step 4:

To a solution of crude 2-(3-(4-(((tert-butyldiphenylsilyl)oxy)methyl)phenyl)-2-oxotetrahydropyrimidin-1 (2H)-yl)ethyl acetate (6.57 g, 12.38 mmol, 1 eq) in THF (40 mL) was added 1 M TBAF solution in THF (18.57 mL, 1.5 eq) at 0° C. The mixture was stirred at 25° C. for 1 h before H₂O (100 mL) was added. The reaction mixture was extracted with EtOAc (4×100 mL). The combined organic layer was washed with brine (50 mL), dried over Na₂SO₄, filtered and concentrated. The water phase was further extracted with CH₂Cl₂ (4×100 mL). The combined organic layer was washed with brine (50 mL), dried over Na₂SO₄, filtered and concentrated to provide more product. Combining both batches of crude product and further purified on silica gel column chromatography (40-100% EtOAc in petroleum ether) to provide 2-(3-(4-(hydroxymethyl)phenyl)-2-oxotetrahydropyrimidin-1 (2H)-yl)ethyl acetate (3.14 g) as as a white solid.

Step 5:

To a mixture of 2-(3-(4-(hydroxymethyl)phenyl)-2-oxotetrahydropyrimidin-1 (2H)-yl)ethyl acetate (1.28 g, 4.38 mmol, 1 eq) and DMF (3.37 uL, 43.79 umol, 0.01 eq) in DCM (25 mL) at 0° C. was added SOCl₂ (5 mL, 68.92 mmol, 15.74 eq). The mixture was stirred at 50° C. for 2 h before it was concentrated to give crude 2-(3-(4-(chloromethyl)phenyl)-2-oxo-tetrahydropyrimidin-1 (2H)-yl)ethyl acetate (1.51 g) which was used in the next step without further purification.

Step 6:

To a solution of crude 2-(3-(4-(chloromethyl)phenyl)-2-oxotetrahydropyrimidin-1 (2H)-yl)ethyl acetate (1.51 g, 4.38 mmol, 1 eq) and of diethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-2,2-dimethyl-6-(prop-1-yn-1-yl)tetrahydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)-malonate (1.91 g, 4.60 mmol, 1.05 eq) in DMF (8 mL) was added Cs₂CO₃ (4.28 g, 13.14 mmol, 3 eq). The mixture was stirred at 25° C. for 16 h before it was diluted with H₂O (40 mL) and extracted with EtOAc (3×30 mL). The combined organic layer was washed with saturated aq. NH₄Cl (2×15 mL), water (2×15 mL), brine (15 mL), dried over Na₂SO₄, filtered and concentrated. The residue was purified by column chromatography on silica gel (25-70% EtOAc in petroleum ether) to provide diethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-6-ethynyl-2,2-dimethyltetrahydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)-2-(4-(3-(2-acetoxy-ethyl)-2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)malonate (2.20 g, 68% yield) as a yellow gum.

Step 7:

To a solution of diethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-6-ethynyl-2,2-dimethyl-tetrahydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)-2-(4-(3-(2-acetoxyethyl)-2-oxotetrahydro-pyrimidin-1 (2H)-yl)benzyl)malonate (2.20 g, 3.19 mmol, 1 eq) in DCM (7.5 mL) was added TFA (7.5 mL, 101.30 mmol, 32 eq) and H₂O (1.5 mL). The mixture was stirred at 25° C. for 16 h before it was diluted with water (20 mL), Then the pH of the mixture was adjusted to 7-8 with NaHCO₃ solid. Then the mixture was extracted with CH₂Cl₂ (4×20 mL). Then the organic phase was washed with brine (10 mL), dried over anhydrous Na₂SO₄, filtered and concentrated to provide crude diethyl 2-(((2R,3S,4R)-3-acetoxy-3-ethynyl-4,5-dihydroxy-tetrahydrofuran-2-yl)methoxy)-2-(4-(3-(2-acetoxyethyl)-2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)malonate (2.1 g) as a yellow gum.

To a solution of the above crude product (2.1 g, 3.19 mmol, 1 eq) in DCM (15 mL) was added Ac₂O (1.79 mL, 19.14 mmol, 6 eq), pyridine (2.06 mL, 25.52 mmol, 8 eq) and 4-DMAP (38.97 mg, 319.00 umol, 0.1 eq). The mixture was stirred at 25° C. for 2 h before it was diluted with EtOAc (100 mL), sequentially washed with 1N aq. HCl (2×30 mL). The organic layer was washed with water (20 mL), saturated aq. NaHCO₃ solution (2×20 mL), water (20 mL), and brine (10 mL). The organic layer was dried over MgSO₄ and concentrated to provide crude diethyl 2-(4-(3-(2-acetoxyethyl)-2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-ethynyltetrahydrofuran-2-yl)methoxy)-malonate (2.3 g) as a yellow foam.

Step 8:

To a solution of 2-chloro-N-methyl-9H-purin-6-amine (151.59 mg, 825.68 umol, 1.1 eq) in MeCN (3 mL) was added BSA (408.19 uL, 1.65 mmol, 2.2 eq). The mixture was stirred at 65° C. for 0.5 h before it was cooled to 0° C. and followed by addition of diethyl 2-(4-(3-(2-acetoxyethyl)-2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (550 mg, crude) in MeCN (3 mL) and TMSOTf (406.91 uL, 2.25 mmol, 3 eq). The mixture was stirred at 65° C. for 3 h before it was allowed to cool to 25° C. and quenched with saturated aq. NaHCO₃ (20 mL). The reaction mixture was extracted with EtOAc (4×20 mL). The combined organic layer was washed with water (10 mL), brine (10 mL), dried over Na₂SO₄, filtered and concentrated. The crude residue was purified by flash column chromatography on silica gel (30-70% EtOAc in petroleum ether) first and then further purified by preparative TLC (7% MeOH in DCM) to provide diethyl 2-(4-(3-(2-acetoxyethyl)-2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(2-chloro-6-(methylamino)-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (180 mg, 22% yield) as a foam.

Step 9:

To a solution of diethyl 2-(4-(3-(2-acetoxyethyl)-2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(2-chloro-6-(methylamino)-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (180 mg, 210.21 umol, 1 eq) in THF (1 mL) was added saturated aq. LiOH solution (1.5 mL). The mixture was stirred at 50° C. for 2 h before the organic volatile was removed under reduced pressure. The pH of the mixture was adjusted to 2-3 with 6N aq. HCl solution and then concentrated. The crude residue was purified by preparative HPLC (column: YMC-Actus ODS-AQ 150*30 5 u; mobile phase: [water (0.225% FA)-ACN]; B %: 15%-35%, 15 min) to provide 2-(((2R,3S,4R,5R)-5-(2-chloro-6-(methylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(3-(2-hydroxyethyl)-2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)malonic acid (71.8 mg, 50% yield) as a white solid.

¹H NMR (400 MHz, CD₃OD) δ ppm 8.14 (s, 1H), 7.27 (d, J=8.0 Hz, 2H), 6.98 (d, J=8.0 Hz, 2H), 5.96 (d, J=7.5 Hz, 1H), 4.76 (d, J=7.4 Hz, 1H), 4.26 (br s, 1H), 4.04 (s, 2H), 3.66 (t, J=5.6 Hz, 2H), 3.36-3.55 (m, 8H), 3.05 (m, 4H), 1.96-2.04 (m, 2H); LC/MS [M+H]=674.1.

Example 138 Synthesis of 2-(((2R,3S,4R,5R)-5-(2-chloro-6-((cyclopropylmethyl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(3-(2-hydroxyethyl)-2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)malonic acid

Proceeding as described in Example 137 above but substituting 2-chloro-N-methyl-9H-purin-6-amine with 2-chloro-N-(cyclopropylmethyl)-9H-purin-6-amine provided the title compound as a white solid.

¹H NMR (400 MHz, CD₃OD) δ ppm 8.09 (s, 1H), 7.28 (d, J=8.3 Hz, 2H), 7.01 (d, J=8.3 Hz, 2H), 5.96 (d, J=7.5 Hz, 1H), 4.74 (d, J=7.3 Hz, 1H), 4.26 (t, J=2.8 Hz, 1H), 4.04 (d, J=2.3 Hz, 2H), 3.62-3.69 (m, 2H), 3.45-3.54 (m, 4H), 3.34-3.42 (m, 6H), 3.06 (s, 1H) 1.97-2.05 (m, 2H), 1.09-1.21 (m, 1H), 0.52-0.61 (m, 2H), 0.34 (q, J=4.8 Hz, 2H); LC/MS [M+H]=714.1

Example 139 Synthesis of 2-(((2R,3S,4R,5R)-5-(2-chloro-6-(isopropylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(3-(2-hydroxyethyl)-2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)malonic acid

Proceeding as described in Example 137 above but substituting 2-chloro-N-methyl-9H-purin-6-amine with 2-chloro-N-isopropyl-9H-purin-6-amine provided the title compound as a white solid.

¹H NMR (400 MHz, CD₃OD) δ ppm 8.08 (s, 1H), 7.29 (d, J=8.3 Hz, 2H), 7.02 (d, J=8.3 Hz, 2H), 5.95 (d, J=7.5 Hz, 1H), 4.73 (d, J=7.5 Hz, 1H), 4.39 (br s, 1H), 4.26 (t, J=2.5 Hz, 1H), 4.04 (d, J=2.0 Hz, 2H), 3.66 (t, J=5.8 Hz, 2H), 3.37-3.52 (m, 9H), 1.97-2.04 (m, 2H), 1.30 (d, J=6.3 Hz, 6H); LC/MS [M+H]=702.1.

Example 140 Synthesis of 2-(((2R,3S,4R,5R)-5-(2-chloro-6-(isopropylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)malonic acid

Proceeding as described in Example 133 above but substituting thymine with 2-chloro-N-isopropyl-9H-purin-6-amine provided the title compound as a white solid.

¹H NMR (400 MHz, CD₃OD) δ ppm 8.16 (s, 1H) 7.32 (d, J=8.44 Hz, 2H) 7.08 (br d, J=8.31 Hz, 2H) 5.99 (d, J=7.46 Hz, 1H) 4.81 (d, J=7.46 Hz, 1H) 4.41 (br s, 1H) 4.26-4.31 (m, 1H) 3.97-4.12 (m, 2H) 3.40-3.57 (m, 4H), 3.33-3.37 (m, 2H), 3.03 (s, 1H), 1.99 (m, 2H), 1.31 (m, 6H); LC/MS [M+H]=658.3.

Example 141 Synthesis of 2-(((2R,3S,4R,5R)-5-(2-chloro-6-(methylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)malonic acid

Proceeding as described in Example 133 above but substituting thymine with 2-chloro-N-methyl-9H-purin-6-amine provided the title compound as a white solid.

¹H NMR (400 MHz, CD₃OD) δ ppm 8.20 (s, 1H), 7.27 (d, J=8.13 Hz, 2H), 7.00 (d, J=8.00 Hz, 2H), 5.97 (d, J=7.38 Hz, 1H), 4.80 (d, J=7.38 Hz, 1H), 4.27 (s, 1H), 4.04 (m, 2H), 3.37-3.50 (m, 4H), 3.31 (d, J=1.13 Hz, 3H), 3.06 (s, 2H) 3.04 (s, 1H), 1.90-2.00 (m, 2H); LC/MS [M+H]=630.2.

Example 142 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(thiazol-2-ylmethyl)malonic acid

Proceeding as described in Example 15 above but substituting allyl bromide with 2-(bromomethyl)thiazole provided the title compound as a white solid.

¹H NMR (400 MHz, CD₃OD) δ ppm 8.56 (s, 1H), 7.56 (d, J=3.4 Hz, 1H), 7.33 (d, J=3.4 Hz, 1H), 6.00 (d, J=5.6 Hz, 1H), 4.68-4.73 (m, 1H), 4.38 (dd, J=6.3, 3.4 Hz, 1H), 3.98-4.07 (m, 2H), 3.85 (s, 2H), 3.00 (s, 1H); LC/MS [M+H]=524.9.

Example 143 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(thiazol-5-ylmethyl)malonic acid

Proceeding as described in Example 15 above but substituting allyl bromide with 5-(chloromethyl)thiazole provided the title compound as a white solid.

¹H NMR (400 MHz, CD₃OD) δ ppm 8.75 (s, 1H), 8.47 (s, 1H), 7.72 (s, 1H), 6.03 (d, J=7.3 Hz, 1H), 4.97 (d, J=7.3 Hz, 1H), 4.36 (dd, J=4.3, 3.0 Hz, 1H), 4.12-4.18 (m, 1H), 4.04-4.10 (m, 1H), 3.63-3.79 (m, 2H), 3.00 (s, 1H); LC/MS [M+H]=524.9.

Example 144 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(pyrrolidin-1-yl)benzyl)malonic acid

Step 1:

To a solution of diethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-6-ethynyl-2,2-dimethyltetra-hydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)malonate (10.0 g, 24.13 mmol, 1 eq) in DMF (100 mL) was added Cs₂CO₃ (23.59 g, 72.39 mmol, 3 eq) and 1-(bromomethyl)-4-iodo-benzene (10.75 g, 36.20 mmol, 1.5 eq). The suspension was stirred at 20° C. for 1 h before it was diluted with water (200 mL). The resulting mixture was extracted with EtOAc (4×50 mL). The combined organic layer was washed with water (2×200 mL), brine (200 mL), dried over anhydrous Na₂SO₄, filtered and concentrated. The crude residue was purified by flash column chromatography on silica gel (5-20% of EtOAc in petroleum ether) to provide diethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-6-ethynyl-2,2-dimethyltetrahydrofuro[2,3-d][1,3]-dioxol-5-yl)methoxy)-2-(4-iodobenzyl)malonate (11.83 g, 74% yield) as a white solid as a white solid.

Step 2:

To a solution of diethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-6-ethynyl-2,2-dimethyltetra-hydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)-2-(4-iodobenzyl)malonate (2.00 g, 3.17 mmol, 1 eq) in DMA (22 mL) was added K₂CO₃ (1.32 g, 9.52 mmol, 3 eq), CuI (120.84 mg, 634.50 umol, 0.2 eq) and proline (438.30 mg, 3.81 mmol, 1.2 eq). The green suspension was stirred at 80° C. under N₂ atmosphere for 16 h before it was allowed to cool and poured into water (40 mL) and 2N aq. LiOH (1 mL). The mixture was extracted with ethyl acetate (2×30 mL). The resulting aq. layer was acidified to pH 5 with 1N aq. HCl solution and then extracted with ethyl acetate (2×40 mL). The combined organic layer was washed with water (80 mL), brine (80 mL), dried over Na₂SO₄, filtered and concentrated to give crude (S)-1-(4-(2-(((3aR,5R,6R,6aR)-6-acetoxy-6-ethynyl-2,2-dimethyltetrahydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)-3-ethoxy-2-(ethoxycarbonyl)-3-oxopropyl)phenyl)pyrrolidine-2-carboxylic acid (390 mg) as a yellow gum.

Step 3:

To a solution of crude (S)-1-(4-(2-(((3aR,5R,6R,6aR)-6-acetoxy-6-ethynyl-2,2-dimethyltetrahydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)-3-ethoxy-2-(ethoxycarbonyl)-3-oxopropyl)phenyl)pyrrolidine-2-carboxylic acid (420 mg, 680.01 umol, 1 eq) in DMF (5 mL) was added K₂CO₃ (282 mg, 2.04 mmol, 3 eq) and EtI (81.58 uL, 1.02 mmol, 1.5 eq). The mixture was stirred at 20° C. for 0.5 h before it was diluted with water (10 mL), and extracted with ethyl acetate (2×10 mL). The combined organic layer was washed with water (20 mL), brine (20 mL), dried over Na₂SO₄, and filtered and concentrated to give crude diethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-6-ethynyl-2,2-dimethyltetrahydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)-2-(4-((S)-2-(ethoxycarbonyl)pyrrolidin-1-yl)benzyl)malonate (330 mg) as a yellow foam.

Step 4:

To a solution of crude diethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-6-ethynyl-2,2-dimethyltetrahydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)-2-(4-((S)-2-(ethoxycarbonyl)pyro-lidin-1-yl)benzyl)malonate (330 mg, crude) in DCM (4 mL) was added H₂O (0.8 mL) and TFA (4 mL) at 0° C. The solution was stirred at 20° C. for 4.5 h before it was quenched with saturated aq. NaHCO₃ to adjust the pH to 9. The mixture was extracted with ethyl acetate (2×8 mL). The combined organic layer was washed with brine (20 mL), dried over Na₂SO₄, filtered and concentrated to crude diethyl 2-(((2R,3S,4R)-3-acetoxy-3-ethynyl-4,5-dihydroxy-tetrahydrofuran-2-yl)methoxy)-2-(4-((S)-2-(ethoxycarbonyl)pyrrolidin-1-yl)benzyl)malonate (285 mg) as a yellow foam.

Step 5:

To a solution of crude diethyl 2-(((2R,3S,4R)-3-acetoxy-3-ethynyl-4,5-dihydroxytetra-hydrofuran-2-yl)methoxy)-2-(4-((S)-2-(ethoxycarbonyl)pyrrolidin-1-yl)benzyl)malonate (285 mg) in pyridine (4 mL) was added 4-DMAP (172 mg, 1.41 mmol, 3 eq) and Ac₂O (352.60 uL, 3.76 mmol, 8 eq). The solution was stirred at 20° C. for 16 h before it was diluted with water (10 mL), and extracted with ethyl acetate (3×10 mL). The combined organic layer was washed with brine (20 mL), dried by Na₂SO₄, filtered and concentrated. The crude residue was purified by flash column chromatography on silica gel (20-50% of ethyl acetate in petrol ether) to give diethyl 2-(4-((S)-2-(ethoxycarbonyl)pyro-lidin-1-yl)benzyl)-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-ethynyltetrahydrofuran-2-yl)methoxy)-malonate (220 mg, 51% yield for four steps) as a yellow gum.

Step 6:

To a suspension of diethyl 2-(4-((S)-2-(ethoxycarbonyl)pyrrolidin-1-yl)benzyl)-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (50 mg, 72.50 umol, 1 eq) and 6-chloropurine (15 mg, 86.99 umol, 1.2 eq) in MeCN (1 mL) was added BSA (44.80 uL, 181.24 umol, 2.5 eq). The suspension was stirred at 65° C. for 0.5 h before it was cooled down to 0° C. and followed by addition of TMSOTf (32.75 uL, 181.24 umol, 2.5 eq). The mixture was stirred at 65° C. for 1 h before it was poured into saturated aq. NaHCO₃ (3 mL). The reaction mixture was extracted with ethyl acetate (3×3 mL). The combined organic layer was concentrated. The crude residue was purified by preparative TLC (petroleum ether:EtOAc=2:1) to give diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-2-(4-((S)-2-(ethoxy-carbonyl)pyrrolidin-1-yl)benzyl)malonate (33 mg, 57% yield) as a yellow gum.

Step 7:

To a solution of diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-2-(4-((S)-2-(ethoxycarbonyl)pyrrolidin-1-yl)benzyl)malonate (28 mg, 35.03 umol, 1 eq) in THF (2 mL) was added 1M aq. LiOH (701 uL, 20 eq). The mixture was stirred at 20° C. for 4.5 h before the organic volatile was removed under reduced pressure. The aq. layer was acidified to pH 6 with 1N aq. HCl solution before it was concentrated. The crude residue was purified by preparative HPLC (Column: YMC-Triart Prep C18 150*40 mm*7 um; mobile phase: [water (0.225% FA)-ACN]; B %: 15%-35%, 10 min.) and dried by lyophilization to provide 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(pyrrolidin-1-yl)benzyl)malonic acid (2.6 mg) as a white solid.

¹H NMR (400 MHz, CD₃OD) δ ppm 8.21 (s, 1H), 7.05 (d, J=8.53 Hz, 2H), 6.26 (d, J=8.53 Hz, 2H), 5.98 (d, J=7.53 Hz, 1H), 4.92-5.02 (m, 1H), 4.29-4.33 (m, 1H), 4.09 (dd, J=10.16, 2.38 Hz, 1H), 3.97 (dd, J=10.04, 3.01 Hz, 1H), 3.38 (d, J=14.56 Hz, 1H), 3.23 (d, J=14.56 Hz, 1H), 3.02-3.09 (m, 4H), 3.00 (s, 1H), 1.89-1.97 (m, 4H); LC/MS [M+H]=587.1.

Example 145 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-(ethylthio)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-benzylmalonic acid

Step 1:

To a mixture of diethyl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-malonate (300 mg, 349.53 umol, 1 eq) in DMF (3 mL) was added NaSEt (88.20 mg, 1.05 mmol, 3 eq). The mixture was stirred at 20° C. for 20 h before it was partitioned between water (15 mL) and EtOAc (15 mL). The aqueous phase was extracted with EtOAc (2×10 mL). The combined organic layer was washed with brine (10 mL), dried over anhydrous Na₂SO₄, and filtered and concentrated under reduced pressure to to provide crude diethyl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-amino-2-(ethylthio)-9H-purin-9-yl)-3-ethynyl-tetrahydrofuran-2-yl)methoxy)malonate (310 mg) as an oil which was used for next step without further purification.

Step 2:

To a mixture of crude diethyl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-amino-2-(ethylthio)-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (310 mg) in DCM (3 mL) was added TFA (1.5 mL, 20.26 mmol). The mixture was stirred at 20° C. for 2 h before it was neutralized to pH 7-8 with saturated aq. NaHCO₃. The reaction mixture was extracted with EtOAc (3×20 mL). The combined extract was washed with brine (15 mL), dried over anhydrous Na₂SO₄, filtered and concentrated under reduced pressure to provide crude diethyl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-amino-2-(ethylthio)-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate as a foam.

Step 3:

To a mixture of crude diethyl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-amino-2-(ethylthio)-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (280 mg, crude) in THF (3 mL) was added saturated aq. LiOH (3 mL). The mixture was stirred at 55° C. for 1 h before it was cooled to room temperature. The reaction mixture was extracted with EtOAc (3×8 mL). The aqueous phase was adjusted to pH 2-3 with 2M aq. HCl before it was extracted with EtOAc (4×10 mL), dried over anhydrous Na₂SO₄, filtered and concentrated. The crude product was purified by preparative HPLC (column: YMC-Triart Prep C18 150*40 mm*7 um; mobile phase: [water (0.225% FA)-ACN]; B %: 23%-43%, 11 min) and dried by lyophilization to give 2-(((2R,3S,4R,5R)-5-(6-amino-2-(ethylthio)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-benzylmalonic acid (4.4 mg) as a white powder.

¹H NMR (400 MHz, DMSO-d₆) δ ppm 12.59-14.32 (m, 2H), 8.30 (s, 1H), 7.33 (s, 2H), 7.00-7.21 (m, 5H), 6.15 (s, 1H), 6.00 (d, J=6.78 Hz, 1H), 5.82 (d, J=7.53 Hz, 1H), 5.01 (s, 1H), 4.14 (dd, J=6.40, 2.64 Hz, 1H), 3.99 (d, J=13.05 Hz, 1H), 3.83 (s, 1H), 3.58 (s, 1H), 3.17-3.18 (m, 2H), 2.99-3.13 (m, 2H), 1.31 (t, J=7.28 Hz, 3H); LC/MS [M+H]=544.0.

Example 146 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(1-(2-methoxyethyl)-2-oxo-1,2-dihydropyridin-3-yl)benzyl)malonic acid

Proceeding as described in Example 11 above but substituting chloro(methoxy)-methane with 1-chloro-2-methoxyethane provided the title compound as a white solid.

¹H NMR (400 MHz, DMSO-d₆) δ ppm 8.41 (s, 1H), 7.80 (s, 2H), 7.60 (dd, J=6.78, 2.01 Hz, 1H), 7.46 (dd, J=7.03, 2.01 Hz, 1H), 7.35 (d, J=8.28 Hz, 2H), 7.21 (d, J=8.28 Hz, 2H), 7.19-7.24 (m, 1H), 6.26-6.31 (m, 1H), 5.82 (d, J=7.78 Hz, 1H) 4.86 (d, J=7.78 Hz, 1H), 4.17 (d, J=1.76 Hz, 1H), 4.10 (t, J=5.14 Hz, 2H), 4.02 (dd, J=10.29, 4.77 Hz, 1H), 3.78-3.85 (m, 1H), 3.54-3.64 (m, 3H), 3.29 (d, J=2.01 Hz, 2H), 3.24 (s, 3H); LC/MS [M+H]=669.0.

Example 147 Synthesis of 2-(((2R,3S,4R,5R)-5-(2-chloro-6-(methylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxo-1,2-dihydropyridin-3-yl)benzyl)malonic acid

Step 1:

To a solution of diethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-6-ethynyl-2,2-dimethyltetra-hydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)-2-(4-iodobenzyl)malonate (2.0 g, 3.17 mmol, 1 eq) in DCM (15 mL) was added H₂O (3 mL) and TFA (15 mL) at 0° C. The solution was stirred at 25° C. for 16 h before it was quenched with saturated aq. NaHCO₃ (150 mL). The mixture was extracted with ethyl acetate (2×100 mL). The combined organic layer was washed with brine (200 mL), dried over Na₂SO₄, filtered and concentrated to give crude diethyl 2-(((2R,3S,4R)-3-ethynyl-3,4,5-trihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-iodobenzyl)malonate (1.74 g) as a yellow foam.

Step 2:

To a solution of diethyl 2-(((2R,3S,4R)-3-ethynyl-3,4,5-trihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-iodobenzyl)malonate (1.74 g, 3.17 mmol, 1 eq) in pyridine (20 mL) was added 4-DMAP (1.16 g, 9.52 mmol, 3 eq) and Ac₂O (2.38 mL, 25.39 mmol, 8 eq). The solution was stirred at 25° C. for 3 h before it was diluted with water (60 mL) and extracted with ethyl acetate (2×60 mL). The combined organic layer was washed with water (100 mL), brine (100 mL), dried over Na₂SO₄, filtered and concentrated. The crude residue was purified by flash column chromatography on silica gel (10-50% of ethyl acetate in petroleum ether) to give diethyl 2-(4-iodobenzyl)-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-ethynyl-tetrahydrofuran-2-yl)methoxy)malonate (1.85 g, 86% yield for two steps) as a yellow foam.

Step 3:

To a solution of diethyl 2-(4-iodobenzyl)-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-ethynyl-tetrahydrofuran-2-yl)methoxy)malonate (1.00 g, 1.48 mmol, 1 eq) in MeCN (12 mL) was added 2-chloro-N-methyl-9H-purin-6-amine (327 mg, 1.78 mmol, 1.2 eq) and BSA (916 uL, 3.71 mmol, 2.5 eq). The suspension was stirred at 65° C. for 0.5 h before it was cooled down to 0° C. and followed by addition of TMSOTf (804 uL, 4.45 mmol, 3 eq). The resulting mixture was stirred at 65° C. for 1.5 h before it was diluted with saturated aq. NaHCO₃ (10 mL) and extracted with ethyl acetate (2×10 mL). The combined organic layer was washed with brine (25 mL), dried over Na₂SO₄, filtered and concentrated. The crude residue was purified by flash column chromatography on silica gel (10-50% ethyl acetate in petroleum ether) to give diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(2-chloro-6-(methylamino)-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-2-(4-iodobenzyl)malonate (595 mg, 50% yield) as a yellow solid.

Step 4:

To a solution of diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(2-chloro-6-(methyl-amino)-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-2-(4-iodobenzyl)malonate (592 mg, 741.88 umol, 1 eq) in DCM (8 mL) was added 4-DMAP (18 mg, 148.38 umol, 0.2 eq), TEA (413 uL, 2.97 mmol, 4 eq) and (Boc)₂O (324 mg, 1.48 mmol, 2 eq). The solution was stirred at 20° C. for 2 h before it was diluted with saturated aq. NH₄Cl (20 mL) and extracted with ethyl acetate (2×20 mL). The combined organic layer was washed with brine (40 mL), dried over Na₂SO₄, filtered and concentrated. The crude was purified by flash column chromatography on silica gel (15-50% of ethyl acetate in petroleum ether) to give diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-((tert-butoxycarbonyl)(methyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-2-(4-iodobenzyl)malonate (560 mg, 84% yield) as a foam.

Step 5:

To a mixture of diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-((tert-butoxycarbonyl)-(methyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-2-(4-iodobenzyl)malonate (660 mg, 734.89 umol, 1 eq) and (2-hydroxypyridin-3-yl)boronic acid (204.18 mg, 1.47 mmol, 2 eq) in dioxane (6 mL) and H₂O (2 mL) was added Pd(dppf)Cl₂ (53.77 mg, 73.49 umol, 0.1 eq) and K₂CO₃ (304.70 mg, 2.20 mmol, 3 eq). The yellow mixture was degassed with N₂ gas for 10 min before the mixture was stirred at 70° C. for 2.5 h The mixture was diluted with water (5 mL) and extracted with ethyl acetate (3×5 mL). The combined organic layer was dried over Na₂SO₄, filtered and concentrated. The crude was purified by flash column chromatography on silica gel (50-100% of ethyl acetate in petroleum ether) to give diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-((tert-butoxy-carbonyl)(methyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxo-1,2-dihydropyridin-3-yl)benzyl)malonate (146 mg) as a foam.

Step 6:

To a solution of diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-((tert-butoxycarbonyl)-(methyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxo-1,2-dihydropyridin-3-yl)benzyl)malonate (145 mg, 167.58 umol, 1 eq) in DCM (6 mL) was added TFA (1.5 mL, 20.26 mmol, 121 eq). The solution was stirred at 25° C. for 1 h before it was neutralized with saturated aq. NaHCO₃ solution. The mixture was extracted with ethyl acetate (3×12 mL). The combined organic layer was washed with brine (30 mL), dried over Na₂SO₄, filtered and concentrated. The crude was purified by preparative TLC (ethyl acetate) to give diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(2-chloro-6-(methylamino)-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxo-1,2-dihydropyridin-3-yl)benzyl)malonate (110 mg) as a solid.

Step 7:

To a solution of diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(2-chloro-6-(methyl-amino)-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxo-1,2-dihydro-pyridin-3-yl)benzyl)malonate (105 mg, 137.23 umol, 1 eq) in THF (4.5 mL) was added aq. LiOH solution (1 M, 1.5 mL, 11 eq). The mixture was stirred at 25° C. for 4 h before the organic volatile was removed under reduced pressure. The aq. layer was acidified to pH 6 with 1N aq. HCl solution and concentrated. The crude residue was purified by preparative HPLC (Column: YMC-Triart Prep C18 150*40 mm*7 um; mobile phase: [water (0.225% FA)-ACN]; B %: 20%-40%, 10 min) and dried by lyophilization to give 2-(((2R,3S,4R,5R)-5-(2-chloro-6-(methylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)-methoxy)-2-(4-(2-oxo-1,2-dihydropyridin-3-yl)benzyl)malonic acid (6.6 mg) as a white solid.

¹H NMR (400 MHz, DMSO-d₆) δ ppm 8.44 (s, 1H), 8.23 (d, J=3.75 Hz, 1H), 7.48 (d, J=6.63 Hz, 1H), 7.39 (d, J=7.00 Hz, 2H), 7.34 (d, J=5.63 Hz, 1H), 7.13-7.22 (m, 2H), 6.15-6.29 (m, 2H), 6.00 (d, J=6.75 Hz, 1H), 5.82 (d, J=7.38 Hz, 1H), 4.71-4.89 (m, 1H), 4.16 (dd, J=4.94, 2.56 Hz, 1H), 3.86-4.05 (m, 1H), 3.53-3.83 (m, 1H), 3.51 (s, 1H), 3.48-3.30 (m, 5H overlapped under water peak), 2.90 (d, J=4.38 Hz, 3H); LC/MS [M+H]=624.9.

Example 148 Synthesis of 2-(((2R,3S,4R,5R)-5-(2-chloro-6-(methylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(3-methyl-2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)malonic acid

Step 1:

To a solution of 1-(4-(((tert-butyldiphenylsilyl)oxy)methyl)phenyl)tetrahydro-pyrimidin-2 (1H)-one (7.33 g, 16.48 mmol, 1 eq) in DMF at 0° C. was added NaH (725 mg, 60% in mineral oil, 18.13 mmol, 1.1 eq). The mixture was stirred for 15 min and followed by addition of CH₃I (4.10 mL, 65.92 mmol, 4 eq). The reaction mixture was stirred from 0-25° C. over 16 h before it was diluted with H₂O (100 mL) and extracted with EtOAc (3×50 mL). The combined organic layer was washed with brine (100 mL), dried over Na₂SO₄, filtered and concentrated. The crude was purified by flash column chromatography on silica gel (0-50% EtOAc in petroleum ether) to provide 1-(4-(((tert-butyldiphenylsilyl)oxy)-methyl)phenyl)-3-methyltetrahydropyrimidin-2 (1H)-one (3.68 g, 48% yield) as a colourless gum.

Step 2:

To a solution of 1-(4-(((tert-butyldiphenylsilyl)oxy)methyl)phenyl)-3-methyltetra-hydropyrimidin-2 (1H)-one (3.68 g, 8.02 mmol, 1 eq) in THF (35 mL) was added TBAF in THF (1.5 M, 10.70 mL, 2 eq) at 0° C. The reaction mixture was stirred at 25° C. for 1.5 h before it was diluted with H₂O (20 mL) and extracted with EtOAc (3×50 mL). The combined organic layer was washed with brine (50 mL), dried over Na₂SO₄, filtered and concentrated. The crude was purified by flash column chromatography on silica gel (0-5% MeOH in DCM) to provide 1-(4-(hydroxymethyl)phenyl)-3-methyltetrahydropyrimidin-2 (1H)-one (1.06 g, 60% yield) as a yellow solid.

Step 3:

To a solution of 1-(4-(hydroxymethyl)phenyl)-3-methyltetrahydropyrimidin-2 (1H)-one (1.06 g, 4.81 mmol, 1 eq) in DCM (10 mL) and DMF (0.1 mL) was added SOCl₂ (698 uL, 9.62 mmol, 2 eq) at 20-25° C. The reaction mixture was stirred for 0.5 h and additional amount of SOCl₂ (419 uL, 5.77 mmol, 1.2 eq) was added. The resulting mixture was stirred at 40° C. for 1 h before it was concentrated. The residue was azeotroped with DCM (3×10 mL) under reduced pressure to provide crude 1-(4-(chloromethyl)phenyl)-3-methyltetra-hydropyrimidin-2 (1H)-one which was used in the next step without further purification.

Step 4:

To a solution of diethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-6-ethynyl-2,2-dimethyltetra-hydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)malonate (1.78 g, 4.30 mmol, 1 eq) in DMF (20 mL) was added Cs₂CO₃ (4.21 g, 12.91 mmol, 3 eq) at 25° C. The reaction mixture was stirred for 0.5 h and followed by addition of crude 1-(4-(chloromethyl)phenyl)-3-methyltetrahydro-pyrimidin-2 (1H)-one (1.13 g). The reaction mixture was stirred at 25° C. for 16 h before it was diluted with H₂O (50 mL) and extracted with EtOAc (3×20 mL). The combined organic layer was washed with brine (30 mL), dried over Na₂SO₄, filtered and concentrated. The crude was purified by column chromatography on silica gel (0-10% of MeOH in DCM) to provide diethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-6-ethynyl-2,2-dimethyl-tetrahydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)-2-(4-(3-methyl-2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)malonate (2.63 g, 78% yield) as a brown foam.

Step 5:

To a solution of diethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-6-ethynyl-2,2-dimethyltetra-hydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)-2-(4-(3-methyl-2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)malonate (2.62 g, 4.25 mmol, 1 eq) in DCM (25 mL) at 0° C. was added TFA (25 mL, 337.65 mmol, 79 eq) and H₂O (2.5 mL, 138.77 mmol, 33 eq). The reaction mixture was stirred at 20-25° C. for 16 h before it was concentrated under reduced pressure. The residue was azeotroped with DCM (3×20 mL) under reduced pressure to provide crude diethyl 2-(((2R,3S,4R)-3-acetoxy-3-ethynyl-4,5-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(3-methyl-2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)malonate (2.57 g) as a syrup which was used in the next step without further purification.

Step 6:

To a solution of crude diethyl 2-(((2R,3S,4R)-3-acetoxy-3-ethynyl-4,5-dihydroxytetra-hydrofuran-2-yl)methoxy)-2-(4-(3-methyl-2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)-malonate (2.57 g) in DCM (25 mL) at 20-25° C. was added Ac₂O (2.39 mL, 25.50 mmol, 6 eq), 4-DMAP (51.92 mg, 425.00 umol, 0.1 eq) and pyridine (2.74 mL, 34.00 mmol, 8 eq).

The reaction mixture was stirred at 25° C. for 16 h before it was concentrated under reduced pressure. The residue was re-dissolved in EtOAc (50 mL), washed with 1N aq. HCl (40 mL), 10% aq. Cu₂SO₄ (40 mL), saturated aq. NaHCO₃ (40 mL) and brine (40 mL), dried over Na₂SO₄, filtered and concentrated to provide crude diethyl 2-(4-(3-methyl-2-oxotetrahydro-pyrimidin-1 (2H)-yl)benzyl)-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (2.62 g, 53% yield for two steps) which was used in the next step without further purification.

Step 7:

To a solution of 2-chloro-N-methyl-9H-purin-6-amine (181 mg, 983.86 umol, 1.3 eq) in MeCN (2.5 mL) under N₂ atmosphere was added BSA (468 uL, 1.89 mmol, 2.5 eq) at 20-25° C. The reaction mixture was stirred at 65° C. for 0.5 h before it was cooled to 25° C. To this mixture was added crude diethyl 2-(4-(3-methyl-2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (500 mg, 756.81 umol, 1 eq) in MeCN (2.5 mL) and TMSOTf (205 uL, 1.14 mmol, 1.5 eq) and stirred at 65° C. for 5 h before it was quenched with saturated aq. NaHCO₃ (10 mL). The mixture was then extracted with EtOAc (3×10 mL). The combined organic layer was washed with brine (20 mL), dried over anhydrous Na₂SO₄, filtered, and concentrated. The crude was purified by flash column chromatography on silica gel column (0-10% MeOH in DCM) to provide diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(2-chloro-6-(methylamino)-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-2-(4-(3-methyl-2-oxotetrahydro-pyrimidin-1 (2H)-yl)benzyl)malonate (530 mg, 60% yield) as a foam.

Step 8:

To a solution of diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(2-chloro-6-(methyl-amino)-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-2-(4-(3-methyl-2-oxotetra-hydropyrimidin-1 (2H)-yl)benzyl)malonate (540 mg, 688.59 umol, 1 eq) in THF (6 mL) was added LiOH·H₂O (288.96 mg, 6.89 mmol, 10 eq) in H₂O (3 mL) at 25° C. The reaction mixture was stirred at 40° C. for 2 h before the organic volatile was removed under reduced pressure. The aq. phase was acidified to pH 2-3 with 1N aq. HCl solution and then concentrated. The crude was purified by preparative HPLC (column: YMC-Actus Triart C18 150*30 mm*5 um; mobile phase: [water (0.225% FA)-ACN]; B %: 23%-43%, 10 min) and dried by lyophilization to provide 2-(((2R,3S,4R,5R)-5-(2-chloro-6-(methylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(3-methyl-2-oxotetra-hydropyrimidin-1 (2H)-yl)benzyl)malonic acid (77.6 mg, 17% yield) as a white solid.

¹H NMR (400 MHz, DMSO-d₆) δ ppm 13.00-13.93 (s, 2H), 8.37 (s, 1H), 8.23 (d, J=5.01 Hz, 1H), 7.11 (d, J=8.31 Hz, 2H), 6.90 (d, J=8.19 Hz, 2H), 6.15 (s, 1H), 5.98 (s, 1H), 5.81 (d, J=7.58 Hz, 1H), 4.82 (s, 1H), 4.15 (dd, J=4.34, 3.00 Hz, 1H), 3.96 (m, 1H), 3.78 (m, 1H), 3.53 (s, 1H), 3.43-3.52 (m, 2H), 3.23 (m, 2H), 3.20-3.10 (m, 4H overlapped with solvent water peak), 2.91 (m, 2H), 2.81 (s, 3H), 1.95 (m, 2H); LC/MS [M+H]=644.1.

Example 149 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(3-methyl-2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)malonic acid

Proceeding as described in Example 148 above but substituting 2-chloro-N-methyl-9H-purin-6-amine with 2-chloro-9H-purin-6-amine provided the title compound as a white solid.

¹H NMR (400 MHz, CD₃OD) δ ppm 8.21 (s, 1H), 7.26 (m, J=8.28 Hz, 2H), 6.96 (m, J=8.28 Hz, 2H), 5.97 (d, J=7.53 Hz, 1H), 4.70-4.83 (m, 1H), 4.27 (t, J=2.76 Hz, 1H), 3.99-4.07 (m, 2H), 3.32-3.52 (m, 6H), 3.05 (s, 1H), 2.87 (s, 3H), 2.00 (quin, J=5.83 Hz, 2H); LC/MS [M+H]=630.2.

Example 150 Synthesis of 2-(((2R,3S,4R,5R)-5-(2-chloro-6-((cyclopropylmethyl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(3-methyl-2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)malonic acid

Proceeding as described in Example 148 above but substituting 2-chloro-N-methyl-9H-purin-6-amine with 2-chloro-N-(cyclopropylmethyl)-9H-purin-6-amine provided the title compound as a white solid.

¹H NMR (400 MHz, CD₃OD) δ ppm 8.12 (s, 1H), 7.27 (d, J=8.28 Hz, 2H), 7.00 (d, J=7.68 Hz, 2H), 5.96 (d, J=7.53 Hz, 1H), 4.70 (d, J=7.53 Hz, 1H), 4.26 (t, J=2.89 Hz, 1H), 4.03 (br s, 2H), 3.33-3.54 (m, 8H), 3.05 (s, 1H), 2.88 (s, 3H), 1.97-2.04 (m, 2H), 1.11-1.20 (m, 1H), 0.53-0.59 (m, 2H), 0.34 (m, 2H); LC/MS [M+H]=684.3.

Example 151 Synthesis of 2-(((2R,3S,4R,5R)-5-(2-chloro-6-(isopropylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(3-methyl-2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)malonic acid

Proceeding as described in Example 148 above but substituting 2-chloro-N-methyl-9H-purin-6-amine with 2-chloro-N-isopropyl-9H-purin-6-amine provided the title compound as a white solid.

¹H NMR (400 MHz, CD₃OD) δ ppm 8.08 (s, 1H), 7.28 (d, J=8.28 Hz, 2H), 7.00 (d, J=8.53 Hz, 2H), 5.95 (d, J=7.53 Hz, 1H), 4.66-4.80 (m, 1H), 4.32-4.48 (m, 1H), 4.25 (t, J=2.89 Hz, 1H), 4.00-4.08 (m, 2H), 3.34-3.53 (m, 6H), 3.05 (s, 1H), 2.88 (s, 3H), 1.94-2.06 (m, 2H), 1.24-1.35 (m, 6H); LC/MS [M+H]=672.1.

Example 152 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxo-3-propyltetrahydropyrimidin-1 (2H)-yl)benzyl)malonic acid

Proceeding as described in Example 148 above but substituting Mel and 2-chloro-N-methyl-9H-purin-6-amine with 1-bromopropane and 2-chloro-9H-purin-6-amine provided the title compound as a white solid.

¹H NMR (400 MHz, CD₃OD) δ ppm 8.15 (s, 1H), 7.28 (d, J=8.4 Hz, 2H), 6.99 (d, J=8.4 Hz, 2H), 5.97 (d, J=7.5 Hz, 1H), 4.75 (d, J=7.6 Hz, 1H), 4.27 (s, 1H), 3.99-4.11 (m, 2H), 3.46-3.54 (m, 2H), 3.35-3.44 (m, 4H), 3.16-3.27 (m, 2H), 3.05 (s, 1H), 1.97-2.03 (m, 2H), 1.50-1.58 (m, 2H), 0.88 (t, J=7.4 Hz, 3H); LC/MS [M+H]=658.1.

Example 153 Synthesis of 2-(((2R,3S,4R,5R)-5-(2-chloro-6-(isopropylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(1-(2-hydroxyethyl)-2-oxo-1,2-dihydropyridin-3-yl)benzyl)malonic acid

Step 1:

To a solution of diethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-6-ethynyl-2,2-dimethyltetra-hydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)malonate (4.13 g, 9.97 mmol, 1 eq) in DCM (40 mL) at 20° C. was added TFA (40 mL, 540.24 mmol, 54 eq) and H₂O (4 mL, 222.03 mmol, 22 eq). The mixture was stirred at 20° C. for 15 h before it was quenched by saturated aq. NaHCO₃ (200 mL) and extracted with EtOAc (5×50 mL). The combined organic layer was washed brine (200 mL), dried over anhydrous Na₂SO₄, filtered and concentrated to give crude diethyl 2-(((2R,3S,4R)-3-acetoxy-3-ethynyl-4,5-dihydroxytetrahydrofuran-2-yl)-methoxy)malonate (4.14 g) as a light yellow syrup which was used in the next step directly.

To a solution of the above crude product (4.14 g, 12.46 mmol, 1 eq) in pyridine (40 mL) was added Ac₂O (9.33 mL, 99.67 mmol, 8 eq) and 4-DMAP (3.81 g, 31.15 mmol, 2.5 eq). The mixture was stirred at 20° C. for 16 h before it was quenched by water (150 mL) and the resulting solution was extracted with EtOAc (4×50 mL). The combined organic layer was washed with 0.5 N aq. HCl (120 mL) and water (2×100 mL), brine (100 mL), dried over anhydrous Na₂SO₄, filtered and concentrated. The crude residue was purified by flash column chromatography on silica gel (30-50% EtOAc in petroleum ether) to provide diethyl 2-(((2R,3R,4R)-3,4,5-triacetoxy-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (2.60 g) as a syrup.

Step 2:

To a solution of diethyl 2-(((2R,3R,4R)-3,4,5-triacetoxy-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (1.2 g, 2.62 mmol, 1 eq) and 2-chloro-N-isopropyl-9H-purin-6-amine (665 mg, 3.14 mmol, 1.2 eq) in MeCN (15 mL) was added BSA (1.62 mL, 6.54 mmol, 2.5 eq). The suspension was stirred at 65° C. for 0.5 h before it was cooled down to 0° C. To this solution was added TMSOTf (1.45 g, 6.54 mmol, 1.18 mL, 2.5 eq). Then the mixture was stirred at 65° C. for 2.5 h before it was quenched by saturated aq. NaHCO₃ (50 mL) and the resulting solution was extracted with EtOAc (4×30 mL). The combined organic layer was dried over anhydrous Na₂SO₄, filtered and concentrated. The residue was purified by flash column chromatography on silica gel (30-50% of EtOAc in petroleum ether) to provide diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(2-chloro-6-(isopropylamino)-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (814 mg, 51% yield).

Step 3:

To a solution of diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(2-chloro-6-(isopropyl-amino)-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (120 mg, 197 umol, 1 eq) in DMF (1 mL) was added K₂CO₃ (81.56 mg, 590.15 umol, 3 eq) and 3-(4-(bromo-methyl)phenyl)-1-(2-((tert-butyldiphenylsilyl)oxy)ethyl)pyridin-2 (1H)-one (161 mg, 295 umol, 1.5 eq). The mixture was stirred at 20° C. for 1.5 h before it was diluted with water (10 mL) and extracted with EtOAc (4×5 mL). The combined organic layer was washed with water (2×30 mL), dried over anhydrous Na₂SO₄, filtered and concentrated. The residue was purified by flash column chromatography on silica gel (30-60% of EtOAc in petroleum ether) to provide diethyl 2-(4-(1-(2-((tert-butyldiphenylsilyl)oxy)ethyl)-2-oxo-1,2-dihydro-pyridin-3-yl)benzyl)-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(2-chloro-6-(isopropyl-amino)-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (154 mg) as a colorless oil.

Step 4:

To a solution of diethyl 2-(4-(1-(2-((tert-butyldiphenylsilyl)oxy)ethyl)-2-oxo-1,2-dihydropyridin-3-yl)benzyl)-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(2-chloro-6-(isopropyl-amino)-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (150 mg, 139 umol, 1 eq) in THF (1 mL) was added TBAF (1 M, 209 uL, 1.5 eq) and AcOH (5.98 uL, 104.59 umol, 0.75 eq) at 0° C. The mixture was stirred at 20° C. for 16 h before it was diluted with water (5 mL) and the resulting solution was extracted with EtOAc (3×5 mL). The combined organic layer was dried over anhydrous Na₂SO₄, filtered and concentrated. The residue was purified by preparative TLC (petroleum ether:EtOAc=1:4) to provide diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(2-chloro-6-(isopropylamino)-9H-purin-9-yl)-3-ethynyl-tetrahydrofuran-2-yl)methoxy)-2-(4-(1-(2-hydroxyethyl)-2-oxo-1,2-dihydropyridin-3-yl)benzyl)malonate (51 mg, 32% yield) as a white solid.

Step 5:

To a solution of diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(2-chloro-6-(isopropyl-amino)-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-2-(4-(1-(2-hydroxyethyl)-2-oxo-1,2-dihydropyridin-3-yl)benzyl)malonate (50 mg, 60 umol, 1 eq) in THF (0.5 mL) was added sat·LiOH·aq (2.51 mg, 60 umol, 0.5 mL, 1 eq). The mixture was stirred at 20° C. for 2.5 h before the organic volatile was removed under reduced pressure. The resulting aq. solution was acidified to pH 2 with 2 N aq. HCl solution and concentrated. The residue was further purification by preparative HPLC (column: YMC-Triart Prep C18 150*40 mm*7 um; mobile phase: [water (0.225% FA)-ACN]; B %: 28%-48%, 10 min) to provide 2-(((2R,3S,4R,5R)-5-(2-chloro-6-(isopropylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxy-tetrahydrofuran-2-yl)methoxy)-2-(4-(1-(2-hydroxyethyl)-2-oxo-1,2-dihydropyridin-3-yl)benzyl)malonic acid (10.8 mg, 26% yield) as a white solid.

¹H NMR (400 MHz, CD₃OD) δ ppm 8.08 (s, 1H), 7.55 (dd, J=6.7, 1.9 Hz, 1H), 7.21-7.42 (m, 5H), 6.34 (t, J=6.8 Hz, 1H), 5.95 (d, J=7.3 Hz, 1H), 4.74 (d, J=7.3 Hz, 1H), 4.24-4.39 (m, 2H), 4.00-4.14 (m, 4H), 3.76-3.87 (m, 2H), 3.40-3.54 (m, 2H), 3.06 (s, 1H), 1.24 (dd, J=6.4, 2.9 Hz, 6H); LC/MS [M+H]=697.0.

Examples 154 & 155 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(4-methyl-2-oxopiperazin-1-yl)benzyl)malonic acid and 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-((2-((carboxymethyl)(methyl)amino)ethyl)amino)benzyl)malonic acid

Step 1:

To a mixture of tert-butyl 3-oxopiperazine-1-carboxylate (8.7 g, 43.45 mmol, 1.2 eq) and (4-iodophenyl) methanol (8.5 g, 36.32 mmol, 1 eq) in DMF (10 mL) and dioxane (90 mL) was added CuI (1.03 g, 5.43 mmol, 0.15 eq), 2-(hydroxymethyl)-2-methyl-propane-1,3-diol (653 mg, 5.43 mmol, 0.15 eq) and Cs₂CO₃ (35.39 g, 108.62 mmol, 3 eq). The mixture was stirred at 110° C. under N₂ atmosphere for 14 hours before it was cooled. The inorganic solid was filtered off and the filtrate was concentrated in vacuo. The residue was diluted with water (50 mL) and extracted with ethyl acetate (3×50 mL). The combined organic layer was washed with brine (50 mL), dried by Na₂SO₄, filtered and concentrated. The crude residue was purified by flash silica gel chromatography (0-10% of EtOAc in petroleum ether) to provide tert-butyl 4-(4-(hydroxymethyl)phenyl)-3-oxopiperazine-1-carboxylate (6.1 g, 55% yield) as a white solid.

Step 2:

To a solution of tert-butyl 4-(4-(hydroxymethyl)phenyl)-3-oxopiperazine-1-carboxylate (2 g, 6.53 mmol, 1 eq) in DCM (10 mL) was added TFA (5.00 mL, 67.53 mmol, 10.34 eq) at 0° C. The mixture was stirred at 25° C. for 3 h before it was concentrated. The residue was diluted with water (20 mL) and extracted with a mixture of DCM and MeOH (50:1=v:v, 2×20 mL). The combined organic layer was concentrated to provide crude 1-(4-(hydroxymethyl)phenyl)piperazin-2-one (2.45 g) as a colorless oil.

Step 3:

To a solution of crude 1-(4-(hydroxymethyl)phenyl)piperazin-2-one (2.45 g, 11.88 mmol, 1 eq) in MeOH (15 mL) was added HCHO (720 uL, 26.12 mmol, 2.2 eq), AcOH (5 mL, 87.42 mmol, 7.4 eq). The mixture was stirred at 25° C. under N₂ atmosphere for 15 h before NaBH₃CN (2.05 g, 32.65 mmol, 2.75 eq) was added and the resulting mixture was stirred for 2 h. The reaction mixture was concentrated in vacuo. The residue was purified by flash column chromatography on silica gel (10-40% of MeOH in EtOAc) to give 1-(4-(hydroxymethyl)phenyl)-4-methylpiperazin-2-one (1.23 g) as a colorless oil.

Step 4:

To a solution of 1-(4-(hydroxymethyl)phenyl)-4-methylpiperazin-2-one (1.23 g, 5.58 mmol, 1 eq) in DCM (2 mL) was added DMF (0.2 mL) and SOCl₂ (810 uL, 11.17 mmol, 2 eq). The mixture was stirred at 25° C. for 30 min to give white suspension before it was concentrated under reduced pressure to give crude 1-(4-(chloromethyl)phenyl)-4-methyl-piperazin-2-one (1.27 g, 95% yield) as a white solid which was used in the next step directly.

Step 5:

To a solution of diethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-6-ethynyl-2,2-dimethyltetra-hydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)malonate (1.4 g, 3.38 mmol, 1 eq) in DMF (15 mL) was added Cs₂CO₃ (3.30 g, 10.14 mmol, 3 eq) and crude 1-(4-(chloromethyl)-phenyl)-4-methylpiperazin-2-one (1.21 g, 5.07 mmol, 1.5 eq). The mixture was stirred at 25° C. for 1 h before it was filtered and the filtrate was concentrated. The crude residue was purified by flash column chromatography on silica gel (0-50% MeOH in EtOAc) to give diethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-6-ethynyl-2,2-dimethyltetrahydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)-2-(4-(4-methyl-2-oxopiperazin-1-yl)benzyl)malonate (1.02 g).

Step 6:

To a solution of diethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-6-ethynyl-2,2-dimethyltetra-hydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)-2-(4-(4-methyl-2-oxopiperazin-1-yl)benzyl)-malonate (1.02 g, 1.65 mmol, 1 eq) in DCM (5 mL) and water (1 mL, 55.51 mmol, 34 eq) was added TFA (4.99 mL, 67.36 mmol, 41 eq). The mixture was stirred at 25° C. for 20 h before it was concentrated to give crude diethyl 2-(((2R,3S,4R)-3-ethynyl-3,4,5-trihydroxy-tetrahydrofuran-2-yl)methoxy)-2-(4-(4-methyl-2-oxopiperazin-1-yl)benzyl)malonate (1.13 g) as an oil.

To a solution of diethyl 2-[[(2R,3S,4R)-3-ethynyl-3,4,5-trihydroxy-tetrahydrofuran-2-yl]methoxy]-2-[[4-(4-methyl-2-oxo-piperazin-1-yl)phenyl]methyl]propanedioate (1.13 g, 2.11 mmol, 1 eq) in DCM (10 mL) was added 4-DMAP (25.78 mg, 211.00 umol, 0.1 eq), pyridine (1.07 mL, 13.2 mmol, 6.3 eq) and Ac₂O (927 uL, 9.9 mmol, 4.7 eq). The mixture was stirred at 25° C. for 16 h before it was concentrated. The residue was diluted with EtOAc (20 mL) and 1N aq. HCl (10 mL). The organic layer was separated and the aqueous layer was extracted with EtOAc (4×20 mL). The combined organic layer was washed with water (50 mL), brine (50 mL) and dried over anhydrous Na₂SO₄, filtered and concentrated to provide crude diethyl 2-(4-(4-methyl-2-oxopiperazin-1-yl)benzyl)-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (674 mg) as an syrup.

Step 7:

To a solution of 2-chloro-9H-purin-6-amine (76 mg, 450.46 umol, 1.2 eq) in dichloroethane (3 mL) was added BSA (204 uL, 825.84 umol, 2.2 eq). The mixture was stirred at 65° C. for 0.5 h before it was cooled to 0° C. and crude diethyl 2-(4-(4-methyl-2-oxopiperazin-1-yl)benzyl)-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (248 mg, 375.38 umol, 1 eq) in dichloroethane (1 mL) and TMSOTf (102 uL, 563.07 umol, 1.5 eq) was added. The mixture was stirred at 65° C. for 2 h under N₂ atmosphere before it was quenched with saturated aq. NaHCO₃ (15 mL) and extracted with EtOAc (4×20 mL). The combined organic layer was dried over anhydrous Na₂SO₄, filtered and concentrated. The residue was purified by flash column chromatography on silica gel (0-30% of MeOH in EtOAc) to provide diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-2-(4-(4-methyl-2-oxo-piperazin-1-yl)benzyl)malonate (62 mg) as a white solid.

Step 8:

To a solution of diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-2-(4-(4-methyl-2-oxopiperazin-1-yl)benzyl)malonate (171 mg, 222.02 umol, 1 eq) in THF (2 mL) was added aq. LiOH (5.32 mg, 222.02 umol, 2 mL, 1 eq). The mixture was stirred at 25° C. for 2.5 h before it was acidified to pH 2-3 with 2N aq. HCl. The mixture was concentrated under reduced pressure. The crude residue was further purified by preparative HPLC to provide 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxy-tetrahydro-furan-2-yl)methoxy)-2-(4-(4-methyl-2-oxopiperazin-1-yl)benzyl)-malonic acid (3.3 mg) as an off-white solid and 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-((2-((carboxymethyl)(methyl)amino)ethyl)-amino)benzyl)malonic acid (3.7 mg) as a white solid.

2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydro-furan-2-yl)methoxy)-2-(4-(4-methyl-2-oxopiperazin-1-yl)benzyl)malonic acid: ¹H NMR (400 MHz, CD₃OD) δ ppm 8.35 (s, 1H), 7.35 (d, J=8.3 Hz, 2H), 6.97 (d, J=8.5 Hz, 2H), 5.95 (d, J=5.5 Hz, 1H), 4.70-4.79 (m, 1H), 4.33 (dd, J=9.0, 3.3 Hz, 1H), 3.96-4.14 (m, 2H), 3.54-3.66 (m, 2H), 3.49 (s, 2H), 3.35 (s, 1H), 3.21 (s, 2H), 2.83 (t, J=5.4 Hz, 2H), 2.32-2.48 (m, 3H), 1.89 (s, 3H); LC/MS [M+H]=630.2.

2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydro-furan-2-yl)methoxy)-2-(4-((2-((carboxymethyl)(methyl)amino)ethyl)amino)benzyl)malonic acid: ¹H NMR (400 MHz, CD₃OD) δ ppm 8.56 (s, 1H), 7.03 (d, J=8.5 Hz, 2H), 6.49 (d, J=8.3 Hz, 2H), 6.01 (d, J=6.0 Hz, 1H), 4.70 (d, J=6.0 Hz, 1H), 4.34 (br d, J=4.3 Hz, 1H), 3.94 (dd, J=9.7, 6.9 Hz, 1H), 3.83 (dd, J=9.9, 2.4 Hz, 1H), 3.59 (s, 2H), 3.34-3.42 (m, 2H), 3.22-3.27 (m, 2H), 3.20 (s, 2H), 3.04 (s, 1H), 2.83 (s, 3H); LC/MS [M+H]=649.3.

Example 156 Synthesis of 2-(((2R,3S,4R,5R)-5-(5-chloro-7-((2,4-dimethoxybenzyl)amino)-3H-imidazo[4,5-b]pyridin-3-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)malonic acid

Step 1:

To a mixture of 5,7-dichloro-3H-imidazo[4,5-b]pyridine (317 mg, 1.69 mmol, 1 eq) in MeCN (6 mL) was added BSA (1.04 mL, 4.22 mmol, 2.5 eq). The mixture was stirred at 65° C. under N₂ atmosphere for 0.5 h before it was cooled to 0° C. To the mixture was added diethyl 2-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (1.20 g, 1.85 mmol, 1.1 eq) and TMSOTf (913.99 uL, 5.06 mmol, 3 eq). The mixture was stirred at 65° C. under N₂ atmosphere for 6 h before it was quenched with NaHCO₃ (15 mL). The reaction mixture was extracted with EtOAc (3×15 mL). The combined organic layer was washed with brine (2×5 mL), dried over Na₂SO₄, filtered and concentrated under reduced pressure. The crude residue was purified by flash column chromatography on silica gel (0-100% of EtOAc in petroleum ether) to provide diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(5,7-dichloro-3H-imidazo[4,5-b]pyridin-3-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)malonate (752 mg) as a foam.

Step 2:

To a mixture of diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(5,7-dichloro-3H-imidazo[4,5-b]pyridin-3-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)malonate (752 mg, 970.82 umol, 1 eq) and 2,4-dimethoxybenzylamine (292 uL, 1.94 mmol, 2 eq) and DIEA (507 uL, 2.91 mmol, 3 eq) were taken up into a microwave tube in NMP (4 mL). The sealed tube was irradiated in a microwave reactor at 130° C. for 2 h before it was diluted with H₂O (10 mL) and extracted with EtOAc (3×15 mL). The combined organic layer was washed with brine (10 mL), dried over Na₂SO₄, filtered and concentrated under reduced pressure. The crude residue was purified by flash column chromatography on silica gel (0-100% of EtOAc in petroleum) to provide diethyl 2-(((2R,3S,4R,5R)-5-(5-chloro-7-((2,4-dimethoxybenzyl)amino)-3H-imidazo-[4,5-b]pyridin-3-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxotetra-hydropyrimidin-1 (2H)-yl)benzyl)malonate (249 mg, 26% yield) as a foam.

Step 3:

To a mixture of diethyl 2-(((2R,3S,4R,5R)-5-(5-chloro-7-((2,4-dimethoxybenzyl)-amino)-3H-imidazo[4,5-b]pyridin-3-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)-methoxy)-2-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)malonate (239 mg, 291.01 umol, 1 eq) in THF (4 mL) and H₂O (3 mL) was added LiOH (69.69 mg, 2.91 mmol, 10 eq). The mixture was stirred at 25° C. for 20 h before it was acidified to pH 6-7 with 2N aqueous HCl and concentrated under reduced pressure. The crude residue was purified by preparative HPLC (column: Phenomenex Gemini-NX 150*30 mm*5 um; mobile phase: [water (0.1% TFA)-ACN]; B %: 25%-65%, 10 min) and dried by lyophilization to provide 2-(((2R,3S,4R,5R)-5-(5-chloro-7-((2,4-dimethoxybenzyl)amino)-3H-imidazo[4,5-b]pyridin-3-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)malonic acid (9.5 mg) as a white solid.

¹H NMR (400 MHz, CD₃OD) δ ppm 8.23 (s, 1H), 7.27 (d, J=8.44 Hz, 2H), 7.21 (d, J=8.31 Hz, 1H), 7.00 (d, J=8.44 Hz, 2H), 6.58 (d, J=2.32 Hz, 1H), 6.46-6.51 (m, 2H), 6.04 (d, J=7.34 Hz, 1H), 4.73 (d, J=7.34 Hz, 1H), 4.43 (s, 2H), 4.27 (t, J=3.06 Hz, 1H), 4.01 (d, J=2.93 Hz, 2H), 3.87 (s, 3H), 3.78 (s, 3H), 3.37-3.47 (m, 2H), 3.31-3.37 (m, 2H), 3.22 (t, J=5.87 Hz, 2H), 3.03 (s, 1H), 1.78-1.85 (m, 2H); LC/MS [M+H]=765.1.

Example 157 Synthesis of 2-(((2R,3S,4R,5R)-5-(7-amino-5-chloro-3H-imidazo[4,5-b]pyridin-3-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)malonic acid

To a mixture of 2-(((2R,3S,4R,5R)-5-(5-chloro-7-((2,4-dimethoxybenzyl)amino)-3H-imidazo[4,5-b]pyridin-3-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)malonic acid (160 mg, 209.11 umol, 1 eq) in DCM (3 mL) was added TFA (1 mL, 13.51 mmol, 64.59 eq). The mixture was stirred at 25° C. for 2 h before it was concentrated. The residue was purified by preparative HPLC (column: YMC-Actus Triart C18 150*30 mm*5 um; mobile phase: [water (0.225% FA)-ACN]; B %: 20%-40%, 10 min) and dried by lyophilization to provide 2-(((2R,3S,4R,5R)-5-(7-amino-5-chloro-3H-imidazo[4,5-b]pyridin-3-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)-methoxy)-2-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)malonic acid (5.4 mg) as a white solid.

¹H NMR (400 MHz, CD₃OD) δ ppm 8.34 (s, 1H), 7.28 (d, J=8.31 Hz, 2H), 7.02 (d, J=8.44 Hz, 2H), 6.49 (s, 1H), 6.07 (d, J=7.21 Hz, 1H), 4.78 (d, J=7.21 Hz, 1H), 4.30 (t, J=3.18 Hz, 1H), 3.93-4.08 (m, 2H), 3.45-3.54 (m, 2H), 3.35-3.49 (m, 4H), 3.04 (s, 1H), 1.94-2.00 (m, 2H); LC/MS [M+H]=615.1.

Example 158 Synthesis of 2-((1H-pyrazol-5-yl)methyl)-2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

Proceeding as described in Example 1 above but substituting benzyl bromide with tert-butyl 5-(bromomethyl)-1H-pyrazole-1-carboxylate provided the title compound as a white solid.

¹H NMR (400 MHz, CD₃OD) δ ppm 8.46 (s, 1H), 7.32 (s, 1H), 6.17 (s, 1H), 6.02 (d, J=7.13 Hz, 1H), 4.83 (s, 1H), 4.34 (s, 1H), 3.98-4.11 (m, 2H), 3.43-3.54 (m, 2H), 2.95 (s, 1H); LC/MS [M+H]=508.1.

Example 159 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-(1-tosyl-1H-pyrazol-4-yl)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

Step 1:

To a mixture of diethyl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(2,6-dichloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (1.3 g, 1.92 mmol, 1 eq) and 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1-tosyl-1H-pyrazole (669 mg, 1.92 mmol, 1 eq) in dioxane (10 mL) and H₂O (3 mL) under a N₂ atmosphere was added Pd(PPh₃)₄ (222 mg, 192 umol, 0.1 eq) and Cs₂CO₃ (1.88 g, 5.76 mmol, 3 eq). The mixture was stirred at 100° C. for 3 h before it was filtered and the filtrate was concentrated under reduced pressure. The crude residue was purified by flash silica gel column chromatography (0-50% of EtOAc in petroleum ether) to provide diethyl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(2-chloro-6-(1-tosyl-1H-pyrazol-4-yl)-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (170 mg) as a foam.

Step 2:

To a solution diethyl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(2-chloro-6-(1-tosyl-1H-pyrazol-4-yl)-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (50 mg, 58 umol, 1 eq) in THF (1 mL) was added 1M aq. LiOH (1 mL, 18 eq). The mixture was stirred at 25° C. for 14 h before it was diluted with EtOAc (10 mL) and water (10 mL). The aqueous phase was adjusted to pH 2-3 with 2M aq. HCl solution and extracted with EtOAc (2×40 mL), dried over anhydrous Na₂SO₄, filtered and concentrated under reduced pressure. The crude residue was purified by preparative HPLC (column: YMC-Triart Prep C18 150*40 mm*7 um; mobile phase: [water (0.225% FA)-AC]; B %: 40%-60%, 10 min) to provide 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-(1-tosyl-1H-pyrazol-4-yl)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid (2.0 mg) as a white solid.

¹H NMR (400 MHz, CD₃OD) δ ppm 8.98 (s, 1H), 8.69 (s, 2H) 7.47 (d, J=8.25 Hz, 2H), 7.30 (d, J=6.88 Hz, 2H), 7.07-7.19 (m, 4H), 6.92 (d, J=8.00 Hz, 2H), 6.24 (d, J=7.63 Hz, 1H), 5.85 (d, J=7.63 Hz, 1H), 4.35 (t, J=2.56 Hz, 1H), 4.03-4.09 (m, 1H), 3.90 (d, J=10.63 Hz, 1H), 3.40-3.50 (m, 1H), 2.92 (s, 1H), 2.05 (s, 3H); LC/MS [M+H]=723.2.

Example 160 Synthesis of 2-(((2R,3S,4R,5R)-5-(2-chloro-6-(methylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxo-1-propyl-1,2-dihydropyridin-3-yl)benzyl)malonic acid

Proceeding as described in Example 19 above but substituting diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-N,N′-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate with diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-((tert-butoxycarbonyl)(methyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyl-tetrahydrofuran-2-yl)methoxy)malonate provided the title compound as a white solid.

¹H NMR (400 MHz, DMSO-d₆) δ ppm 8.44 (s, 1H), 8.25 (d, J=4.3 Hz, 1H), 7.68 (dd, J=6.7, 1.8 Hz, 1H), 7.29-7.51 (m, 3H), 7.18 (d, J=7.5 Hz, 2H), 6.28 (t, J=6.8 Hz, 1H), 6.21 (s, 1H), 6.01 (d, J=6.8 Hz, 1H), 5.83 (d, J=7.3 Hz, 1H), 4.82 (s, 1H), 4.17 (dd, J=5.1, 2.6 Hz, 1H), 3.96 (s, 1H), 3.89 (t, J=7.3 Hz, 2H), 3.79 (s, 1H), 3.58 (s, 1H), 3.25 (s, 1H), 2.90 (d, J=4.5 Hz, 3H), 1.67 (sxt, J=7.3 Hz, 2H), 0.88 (t, J=7.4 Hz, 3H); LC/MS [M+H]=667.1.

Example 161 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-(1-hydroxyethyl)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-benzylmalonic acid

Step 1:

To a solution of diethyl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(2-acetyl-6-amino-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (48 mg, 72.11 umol, 1 eq) in MeOH (2 mL) at 0° C. was added NaBH₄ (4.09 mg, 108.17 umol, 1.5 eq). The solution was stirred at 0° C. for 1 h. Additional NaBH₄ (4.1 mg) was added to the reaction mixture and it was stirred at 0° C. for 0.5 h before it was diluted with water (6 mL) and extracted with ethyl acetate (3×6 mL). The combined organic layer was dried by Na₂SO₄, filtered and concentrated. The crude residue was purified by preparative TLC (ethyl acetate) to give diethyl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-amino-2-(1-hydroxyethyl)-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (20 mg) as a syrup.

Step 2:

To a solution of diethyl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-amino-2-(1-hydroxyethyl)-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (16 mg, 23.96 umol, 1 eq) in THF (2 mL) was added 1M aq. LiOH (0.5 mL, 21 eq). The mixture was stirred at 20° C. for 3 h before it was acidified to pH 5 with 1N aq. HCl solution. The mixture was extracted with ethyl acetate (5×3 mL). The combined organic layer was concentrated. The crude residue was purified by preparative HPLC (Column: YMC-Triart Prep C18 150*40 mm*7 um; mobile phase: [water (0.225% FA)-ACN]; B %: 13%-33%, 10 min) and dried by lyophilization to give 2-(((2R,3S,4R,5R)-5-(6-amino-2-(1-hydroxyethyl)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-benzylmalonic acid (4.0 mg) as a white solid.

¹H NMR (400 MHz, CD₃OD) δ ppm 8.49 (d, J=8.88 Hz, 1H), 7.18-7.25 (m, 2H), 7.07-7.14 (m, 3H), 6.09 (dd, J=9.82, 6.94 Hz, 1H), 4.76-4.84 (m, 2H), 4.29-4.36 (m, 1H), 3.89-4.03 (m, 2H), 3.32-3.45 (m, 1H), 3.24-3.28 (m, 1H), 3.02 (d, J=10.13 Hz, 1H), 1.52 (d, J=6.50 Hz, 3H); LC/MS [M+H]=528.1.

Example 162 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(1-methyl-2-oxo-1,2-dihydropyridin-3-yl)benzyl)malonic acid

Proceeding as described in Example 19 above but substituting 3-(4-(bromomethyl)-phenyl)-1-propylpyridin-2 (1H)-one with 3-(4-(bromomethyl)phenyl)-1-methylpyridin-2 (1H)-one provided the title compound as a white solid.

¹H NMR (400 MHz, CD₃OD) δ ppm 8.12 (s, 1H), 7.55-7.53 (m, 1H), 7.38-7.28 (m, 5H), 6.33 (t, J=6.8 Hz, 1H), 5.94 (d, J=7.6 Hz, 1H), 4.75 (d, J=7.6 Hz, 1H), 4.27-4.26 (m, 1H), 4.09-4.01 (m, 2H), 3.55 (s, 3H), 3.53-3.44 (m, 2H), 3.05 (s, 1H); LC/MS [M+H]=625.0.

Example 163 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(6-(3-carboxypropyl)-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

Step 1:

To a solution of 2,6-dichloro-9-(tetrahydro-2H-pyran-2-yl)-9H-purine (4.00 g, 14.65 mmol, 1 eq) and Pd(Ph3P)4 (1.69 g, 1.46 mmol, 0.1 eq) in THF (30 mL) under N₂ atmosphere at 0° C. was added a solution of 0.5 M (4-ethoxy-4-oxobutyl)zinc(II) bromide (73.23 mL, 36.61 mmol, 2.5 eq) dropwise. The mixture was stirred from 0-25° C. over 16 h before it was cooled to 0° C. and quenched with 0.5N aq. HCl solution. The reaction mixture was extracted with EtOAc (3×100 mL). The combined organic extract was washed with H₂O (100 mL), brine (50 mL), dried over Na₂SO₄, filtered and concentrated. The crude residue was purified by flash column chromatography on silica gel (10-75% EtOAc in petroleum ether) to provide ethyl 4-(2-chloro-9-(tetrahydro-2H-pyran-2-yl)-9H-purin-6-yl)butanoate (2.83 g).

Step 2:

To a solution of ethyl 4-(2-chloro-9-(tetrahydro-2H-pyran-2-yl)-9H-purin-6-yl)-butanoate (1.50 g, 4.25 mmol) in DCM (15 mL) was added TFA (10 mL). The mixture was stirred at 25° C. for 7 h before it was concentrated under reduced pressure. The residue was re-taken up in H₂O (50 mL) and neutralized to pH 7 with saturated aq. NaHCO₃. The resulting mixture was extracted with EtOAc (3×75 mL). The combined organic layer was washed with brine, dried over Na₂SO₄, filtered and concentrated to provide ethyl 4-(2-chloro-9H-purin-6-yl)butanoate (1.05 g).

Steps 3-4:

Proceeding as described in Example 5 above but substituting uracil with ethyl 4-(2-chloro-9H-purin-6-yl)butanoate provided the title compound as a white solid.

¹H NMR (400 MHz, CD₃OD) δ ppm 8.74 (s, 1H), 7.27-7.24 (m, 2H), 7.09-7.08 (m, 3H), 6.09 (d, J=7.6 Hz, 1H), 5.05 (d, J=7.6 Hz, 1H), 4.31-4.14 (m, 1H), 4.10-4.06 (m, 2H), 3.18-3.16 (m, 3H), 2.41 (t, J=7.2 Hz, 2H), 2.17-2.15 (m, 2H), 1.22 (t, J=7.6 Hz, 2H); LC/MS [M+H]=589.1.

Examples 164 and 165 Synthesis of (R)-2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-ethoxy-3-oxo-2-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)propanoic acid and (S)-2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-ethoxy-3-oxo-2-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)propanoic acid

Step 1:

To a suspension of 2-chloro-9H-purin-6-amine (1.04 g, 6.15 mmol, 1.7 eq) in MeCN (10 mL) at 25° C. was added N,O-bis(trimethylsilyl)acetamide (BSA) (3.1 mL, 0.0127 mol, 3.5 eq). The resulting suspension was heated at 85° C. for 30 min as it became clear. The reaction mixture was allowed to cool to 25° C. followed by addition of a solution of diethyl 2-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)-2-(((2R,3R,4R)-3,4,5-triacetoxy-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (2.34 g, 0.0036 mol, 1.0 eq) in MeCN (10 mL) and TMSOTf (1.12 mL, 0.00615 mol, 1.7 eq) dropwise. The reaction mixture was then heated at 70-80° C. overnight as all of the starting material was consumed. The reaction was allowed to cool to 25° C. before it was diluted with MeCN (100 mL) and quenched with saturated aq. NaHCO₃ solution (150 mL). The insoluble was removed by filtration. The organic layer of the filtrate was separated, washed with H₂O (50 mL), brine (50 mL), dried over Na₂SO₄ and concentrated. The crude residue was purified by flash silica gel column chromatography (0-5% MeOH in CH₂Cl₂) to provide diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)malonate (1.1 g, 40% yield) as a white solid.

Step 2:

To a solution of diethyl 2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-2-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)malonate (400 mg, 0.53 mmol, 1 eq) in THF (4 mL) and H₂O (4 mL) at 0° C. was added LiOH monohydrate (89 mg, 2.12 mmol, 4 eq). The resulting mixture was stirred at room temperature overnight before the organic volatile was removed under reduced pressure. The mixture was cooled to 0° C. and acidified to pH 6 with 1N aq. HCl solution and concentrated under reduced pressure. The crude residue was purified by preparative reversed-phase HPLC to provide a pair of diastereomers as a white solid: (R)-2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydro-furan-2-yl)methoxy)-3-ethoxy-3-oxo-2-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)-propanoic acid and (S)-2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-ethoxy-3-oxo-2-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)propanoic acid which the stereo configuration was arbitrarily assigned. In addition, Example 9 was also isolated as a white solid.

(R)-2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetra-hydrofuran-2-yl)methoxy)-3-ethoxy-3-oxo-2-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)propanoic acid: ¹H NMR (300 MHz, CD₃OD) δ 8.32 (s, 1H), 7.28 (d, J=8.1 Hz, 2H), 7.01 (d, J=8.1 Hz, 2H), 6.00 (d, J=7.5 Hz, 1H), 4.84 (d, J=7.5, 1H), 4.28-4.06 (m, 3H), 3.99-3.95 (m, 2H), 3.52-3.35 (m, 6H), 3.08 (s, 1H), 2.02-1.97 (m, 2H), 1.21 (t, J=7.1, 3H); LC/MS [M+H]=644.05.

(S)-2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetra-hydrofuran-2-yl)methoxy)-3-ethoxy-3-oxo-2-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)benzyl)propanoic acid: ¹H NMR (300 MHz, CD₃OD) δ 8.08 (s, 1H), 7.26-7.29 (d, J=6.8 Hz, 2H), 7.03-7.01 (d, J=7.23 Hz, 2H), 5.96-5.99 (d, J=7.14 Hz, 1H), 4.75-4.77 (d, J=7.5, 1H), 4.02-4.24 (m, 5H), 3.32-3.66 (m, 6H), 3.15 (s, 1H), 1.95-2.19 (m, 2H), 1.22-1.27 (m, 3H); LC/MS [M+H]=644.05.

Examples 166 and 167 Synthesis of (R)-2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)phenyl)propanoic acid and (S)-2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)phenyl)propanoic acid

The crude product of Example 9 from the work up was dried in the vacuum oven at 60° C. for 2 days before it was purified by preparative HPLC to provide a pair of diastereomers: (R)-2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)phenyl)-propanoic acid and (S)-2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)phenyl)-propanoic acid which the stereo configuration was arbitrarily assigned. Both were isolated as white solids.

(R)-2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetra-hydrofuran-2-yl)methoxy)-3-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)phenyl)propanoic acid:

¹H NMR (300 MHz, CD₃OD) δ 8.38 (s, 1H), 7.22 (d, J=8.3 Hz, 2H), 7.04 (d, J=8.3 Hz, 2H), 5.92 (d, J=7.3 Hz, 1H), 4.36-4.32 (m, 1H), 4.30 (d, J=7.3 Hz, 1H), 4.17 (t, J=2.3 Hz, 1H), 4.07-4.03 (m, 1H), 3.80-3.75 (m, 1H), 3.54-3.49 (m, 2H), 3.33-3.31 (m, 2H), 3.25-3.19 (m, 1H), 3.12 (s, 1H), 3.09-3.02 (m, 1H), 2.02-1.97 (m, 2H); LC/MS [M+H]=572.0.

(S)-2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetra-hydrofuran-2-yl)methoxy)-3-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)phenyl)propanoic acid:

¹H NMR (300 MHz, CD₃OD) δ 8.47 (s, 1H), 7.26 (d, J=8.2 Hz, 2H), 7.15 (d, J=8.3 Hz, 2H), 5.97 (d, J=7.0 Hz, 1H), 4.97 (d, J=7.0 Hz, 1H), 4.31 (t, J=6.4 Hz, 1H), 4.20 (t, J=3.4 Hz, 1H), 3.91 (d, J=3.4 Hz, 1H), 3.65 (t, J=6.0 Hz, 2H), 3.39-3.33 (m, 2H), 3.23-3.17 (m, 2H), 3.08 (s, 1H), 3.06-3.01 (m, 1H), 2.10-1.95 (m, 2H); LC/MS [M+H]=572.0.

Example 168 Synthesis of 2-benzyl-2-(((2R,3S,4R,5R)-5-(2-chloro-6-(hydroxyamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid

Step 1:

To a solution of diethyl 2-benzyl-2-(((2R,3S,4R,5R)-5-(5-chloro-7-(hydroxyamino)-3H-imidazo[4,5-b]pyridin-3-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-malonate (98 mg, 0.144 mmol) in dioxane (2 mL) was added an aqueous solution of hydroxylamine (0.1 mL, 1.6 mmol, 16 M) and Et₃N (35 uL, 0.16 mmol). The reaction mixture was stirred for 2.5 h and then it was diluted with EtOAc (15 mL) and H₂O (5 mL). The organic layer was separated, washed with H₂O (20 mL), brine (20 mL), dried over Na₂SO₄ and concentrated to provide crude diethyl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(2-chloro-6-(hydroxyamino)-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)-malonate (88 mg) as an off-solid which was used in the next step without further purification.

Step 2:

To a solution of crude diethyl 2-benzyl-2-(((2R,3R,4R,5R)-3,4-diacetoxy-5-(2-chloro-6-(hydroxyamino)-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)malonate (88 mg, 0.14 mmol) in a mixture of THF (0.2 mL), MeOH (0.62 mL) and H₂O (0.15 mL) was added LiOH·H₂O (31 mg, 0.75 mmol). The resulting mixture was stirred at 25° C. for 5.5 h before the organic volatile was removed under reduced pressure. The aq. layer was cooled to 0° C. and acidified to pH 6.5 with 1N aq. HCl solution before it was concentrated. The crude residue was purified by preparative reversed-phase HPLC to provide 2-benzyl-2-(((2R,3S,4R,5R)-5-(5-chloro-7-(hydroxyamino)-3H-imidazo[4,5-b]pyridin-3-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)malonic acid (17 mg) as a reddish solid.

¹H NMR (CD₃OD, 300 MHz) δ 8.25 (s, 1H), 7.25-7.28 (m, 2H), 7.05 (m, 3H), 6.43 (s, 1H), 6.06-6.08 (d, J=7.17 Hz, 1H), 4.95-4.98 (d, J=7.05 Hz, 1H), 4.32 (s, 1H), 4.05-4.11 (m, 2H), 3.89-3.93 (m, 1H), 3.31-3.39 (m, 2H), 2.99 (s, 1H), 1.30-1.33 (m, 6H); LC/MS [M+H]=533.1.

Example 169 Synthesis of 2-(((2R,3S,4R,5R)-5-(2-chloro-6-(isopropylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(thiazol-4-yl)-3-(thiophen-3-yl)propanoic acid

Step 1:

To a solution of ethyl 2-(thiazol-4-yl)acetate (2 g, 11.7 mmole) in CH₃CN (15 mL) at 0° C. was added DBU (2.62 ml, 17.6 mmole) and 4-acetamidibenzene sulfonylazide (3.4 g, 14.1 mmole) in CH₃CN (10 mL). The reaction mixture was stirred at room temperature for 1.5 h before it was concentrated under reduced pressure to dryness. The resulting crude was purified by silica gel column chromatography (0-40% EtOAc in hexanes) to provide ethyl 2-diazo-2-(thiazol-4-yl)acetate (2.0 g).

Step 2:

To a mixture of (3aR,5R,6R,6aR)-6-ethynyl-5-(hydroxymethyl)-2,2-dimethyltetra-hydrofuro[2,3-d][1,3]dioxol-6-yl acetate (7 g, 27.32 mmol, 1 eq) in DCE (15 mL) was added Rh(OAc)₂ (603.69 mg, 2.73 mmol, 0.1 eq) and ethyl 2-diazo-2-(thiazol-4-yl)acetate (6.46 g, 32.78 mmol, 1.2 eq) in DCE (15 mL) dropwise at 0° C. The mixture was stirred at 25° C. under N₂ atmosphere for 14 h before the insoluble was filtered and the filtrate was concentrated under reduced pressure. The crude residue was purified by flash silica gel column chromatography (0-50% of EtOAc in petroleum ether) to provide ethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-6-ethynyl-2,2-dimethyltetrahydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)-2-(thiazol-4-yl)acetate (10.81 g, 93% yield) as an oil.

Step 3:

To a mixture of ethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-6-ethynyl-2,2-dimethyltetra-hydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)-2-(thiazol-4-yl)acetate (2.69 g, 6.33 mmol, 1 eq) in DMF (5 mL) was added Cs₂CO₃ (6.18 g, 18.98 mmol, 3 eq). The mixture was stirred at 25° C. under N₂ atmosphere for 0.5 h before 3-(bromomethyl)thiophene (2.8 g, 15.81 mmol, 2.5 eq) was added. The resulting mixture was stirred at 25° C. for 14 h before the insoluble was filtered and the filtrate was diluted with H₂O (15 mL) and extracted with EtOAc (3×15 mL). The combined organic layer was washed with saturated aq. NH₄Cl (3×15 mL), dried over Na₂SO₄, filtered and concentrated under reduced pressure. The crude residue was purified by flash silica gel column chromatography (0-50% of EtOAc in petroleum) to provide ethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-6-ethynyl-2,2-dimethyltetrahydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)-2-(thiazol-4-yl)-3-(thiophen-3-yl)propanoate (2.27 g, 69% yield) as an oil.

Step 4:

To a mixture of ethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-6-ethynyl-2,2-dimethyltetra-hydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)-2-(thiazol-4-yl)-3-(thiophen-3-yl)propanoate (2.27 g, 4.35 mmol, 1 eq) in DCM (5 mL) and H₂O (0.5 mL) was added TFA (5 mL, 67.53 mmol, 15.5 eq). The mixture was stirred at 15° C. under N₂ atmosphere for 14 h before it was adjusted to 7-8 pH with saturated aq. NaHCO₃ (50 mL) and concentrated under reduced pressure. The residue was diluted with H₂O (5 mL) and extracted with EtOAc (4×15 mL). The combined organic layer was washed with brine (10 mL), dried over Na₂SO₄, filtered and concentrated under reduced pressure to provide crude ethyl 2-[[(2R,3S,4R)-3-acetoxy-3-ethynyl-4,5-dihydroxy-tetrahydrofuran-2-yl]methoxy]-2-thiazol-4-yl-3-(3-thienyl)propanoate (1.82 g) as a syrup.

To a solution of ethyl 2-[[(2R,3S,4R)-3-acetoxy-3-ethynyl-4,5-dihydroxy-tetrahydro-furan-2-yl]methoxy]-2-thiazol-4-yl-3-(3-thienyl)propanoate (1.82 g, 3.78 mmol, 1 eq) in pyridine (8 mL) under a N₂ atmosphere at 0° C. was added 4-DMAP (1.39 g, 11.34 mmol, 3 eq) and Ac₂O (2.83 mL, 30.24 mmol, 8 eq). The mixture was stirred at 15° C. for 15 before it was diluted with H₂O (20 mL) and extracted with EtOAc (3×15 mL). The combined organic layer was washed with 10% CuSO₄ solution (2×15 mL), dried over Na₂SO₄, filtered and concentrated under reduced pressure to give crude (3R,4R,5R)-5-(((1-ethoxy-1-oxo-2-(thiazol-4-yl)-3-(thiophen-3-yl)propan-2-yl)oxy)methyl)-4-ethynyltetrahydrofuran-2,3,4-triyl triacetate (2.42 g) as a syrup.

Step 5:

To a mixture of 2-chloro-N-isopropyl-9H-purin-6-amine (606.20 mg, 2.86 mmol, 1 eq) in DCE (20 mL) was added BSA (1.77 mL, 7.16 mmol, 2.5 eq). The mixture was stirred at 85° C. under a N₂ atmosphere for 0.5 h before it was allowed to cool to 0° C. and followed by addition of crude (3R,4R,5R)-5-(((1-ethoxy-1-oxo-2-(thiazol-4-yl)-3-(thiophen-3-yl)-propan-2-yl)oxy)methyl)-4-ethynyltetrahydrofuran-2,3,4-triyl triacetate (1.62 g, 2.86 mmol, 1 eq) and TMSOTf (1.55 mL, 8.59 mmol, 3 eq). The resulting mixture was stirred at 65° C. under N₂ for 14 h before it was quenched with saturated aq. NaHCO₃ (20 mL). The reaction mixture was diluted with H₂O (10 mL) and extracted with DCM (3×20 mL). The combined organic layer was washed with brine (3×15 mL), dried over Na₂SO₄, filtered and concentrated under reduced pressure. The crude residue was purified by flash silica gel column chromatography (0-50% of EtOAc in petroleum ether) to provide (2R,3R,4R,5R)-5-(2-chloro-6-(isopropylamino)-9H-purin-9-yl)-2-(((1-ethoxy-1-oxo-2-(thiazol-4-yl)-3-(thio-phen-3-yl)propan-2-yl)oxy)methyl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate (402 mg, crude) as a syrup.

Step 6:

To a mixture of (2R,3R,4R,5R)-5-(2-chloro-6-(isopropylamino)-9H-purin-9-yl)-2-(((1-ethoxy-1-oxo-2-(thiazol-4-yl)-3-(thiophen-3-yl)propan-2-yl)oxy)methyl)-3-ethynyltetra-hydrofuran-3,4-diyl diacetate (384 mg, crude) in THF (2 mL) and H₂O (1 mL) was added LiOH (128 mg, 5.35 mmol). The mixture was stirred at 50° C. for 6 h before it was diluted with H₂O (40 mL) and extracted with EtOAc (10 mL). The aqueous phase was acidified to pH 2-3 with 2 N aqueous HCl until pH-2-3 and then concentrated under reduced pressure. The crude residue was purified by preparative HPLC (column: YMC-Actus Triart C18 150*30 mm*5 um; mobile phase: [water (0.225% FA)-ACN]; B %: 40%-60%, 10 min) and dried by lyophilization to provide a diastereomeric mixture (ca. 1:1) of 2-(((2R,3S,4R,5R)-5-(2-chloro-6-(isopropylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(thiazol-4-yl)-3-(thiophen-3-yl)propanoic acid (17.5 mg) as a white solid.

¹H NMR (400 MHz, CD₃OD) δ ppm 8.92-9.01 (m, 1H), 8.04-8.28 (m, 1H), 7.60-7.71 (m, 1H), 7.10-7.15 (m, 1H), 6.98-7.06 (m, 1H), 6.77-6.94 (m, 1H), 5.90-6.02 (m, 1H), 4.91-5.06 (m, 2H), 4.40 (br s, 1H), 4.19-4.32 (m, 1H), 3.89-3.99 (m, 1H), 3.65-3.87 (m, 3H), 2.89-3.02 (m, 1H), 1.25-1.35 (m, 6H); LC/MS [M+H]=605.2.

Examples 170 & 171 Synthesis of (S)-2-(((2R,3S,4R,5R)-5-(2-chloro-6-(isopropylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-phenyl-2-(thiazol-4-yl)propanoic acid and (R)-2-(((2R,3S,4R,5R)-5-(2-chloro-6-(isopropylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-phenyl-2-(thiazol-4-yl)propanoic acid

Proceeding as described in Example 169 above but substituting 3-(bromomethyl)thiophene with benzyl bromide provided a pair of diastereomeric products which the stereo configuration was assigned arbitrarily. Both products were purified by preparative HPLC and isolated as white solids.

(S)-2-(((2R,3S,4R,5R)-5-(2-chloro-6-(isopropylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-phenyl-2-(thiazol-4-yl)propanoic: ¹H NMR (CD₃OD, 300 MHz) δ 8.99 (s, 1H), 7.91 (s, 1H), 7.70 (s, 1H), 7.07-7.23 (m, 5H), 5.91-5.94 (d, J=6.9 Hz, 1H), 4.87-4.90 (d, J=7.0 Hz, 1H), 4.21-4.45 (m, 2H), 3.59-3.94 (m, 4H), 3.02 (s, 1H), 1.29-1.31 (d, J=6.48 Hz, 6H); LC/MS [M+H]=599.0.

(R)-2-(((2R,3S,4R,5R)-5-(2-chloro-6-(isopropylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-phenyl-2-(thiazol-4-yl)propanoic: ¹H NMR (CD₃OD, 300 MHz) δ 8.97-8.98 (d, J=1.83 Hz, 1H), 8.07 (s, 1H), 7.573-7.579 (d, J=1.86 Hz, 1H), 6.94-7.09 (m, 5H), 5.97-5.99 (d, J=7.17 Hz, 1H), 4.98-5.00 (d, J=7.23 Hz, 1H), 4.40-4.42 (m, 1H), 4.27-4.29 (t, J=3.84 Hz, 1H), 3.93-3.97 (m, 2H), 3.59-3.81 (q, J=14.31, 37.47 Hz, 2H), 2.95 (s, 1H), 1.29-1.33 (d, J=6.39 Hz, 6H); LC/MS [M+H]=599.0.

Examples 172 & 173 Synthesis of (S)-2-(((2R,3S,4R,5R)-5-(2-chloro-6-((cyclopropylmethyl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-phenyl-2-(thiazol-4-yl)propanoic acid and (R)-2-(((2R,3S,4R,5R)-5-(2-chloro-6-((cyclopropylmethyl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-phenyl-2-(thiazol-4-yl)propanoic acid

Proceeding as described in Examples 170 and 171 above but substituting 2-chloro-N-isopropyl-9H-purin-6-amine with 2-chloro-N-(cyclopropylmethyl)-9H-purin-6-amine provided a pair of diastereomeric products which the stereo configuration was assigned arbitrarily. Both products were purified by preparative HPLC and isolated as white solids.

(S)-2-(((2R,3S,4R,5R)-5-(2-chloro-6-((cyclopropylmethyl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-phenyl-2-(thiazol-4-yl)propanoic acid:

¹H NMR (CD₃OD, 300 MHz) δ 8.99-8.99 (d, J=1.95 Hz, 1H), 7.93 (s, 1H), 7.69-7.70 (d, J=1.86 Hz, 1H), 7.03-7.23 (m, 5H), 5.92-5.94 (d, J=6.96 Hz, 1H), 4.87-4.89 (d, J=7.11 Hz, 1H), 4.19-4.22 (m, 1H), 3.59-3.94 (m, 4H), 3.42-3.43 (m, 2H), 3.02 (s, 1H), 1.12-1.22 (m, 1H), 0.54-0.61 (m, 2H), 0.32-0.37 (m, 2H); LC/MS [M+H]=611.0.

(R)-2-(((2R,3S,4R,5R)-5-(2-chloro-6-((cyclopropylmethyl)amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-phenyl-2-(thiazol-4-yl)propanoic acid:

¹H NMR (CD₃OD, 300 MHz) δ 8.96-8.97 (d, J=1.89 Hz, 1H), 8.07 (s, 1H), 7.55-7.56 (d, J=2.07 Hz, 1H), 6.94-7.11 (m, 5H), 5.97-5.99 (d, J=7.17 Hz, 1H), 4.98-5.00 (d, J=7.29 Hz, 1H), 4.27-4.29 (t, J=3.66 Hz, 1H), 3.94-3.95 (m, 2H), 3.59-3.80 (q, J=14.64, 32.46 Hz, 2H), 3.39-3.50 (m, 2H), 2.96 (s, 1H), 1.13-1.23 (m, 1H), 0.55-0.62 (m, 2H), 0.32-0.38 (m, 2H); LC/MS [M+H]=611.0.

Example 174 Synthesis of 2-(((2R,3S,4R,5R)-5-(2-chloro-6-(isopropylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(thiazol-4-yl)-3-(4-(trifluoromethoxy)phenyl)propanoic acid

Proceeding as described in Example 169 above but substituting 3-(bromomethyl)thiophene with 1-(bromomethyl)-4-(trifluoromethoxy)benzene provided the title compound as a mixture of diastereomers (ca. 1:1) and isolated as a white solid.

¹H NMR (400 MHz, CD₃OD) δ ppm 8.95-9.02 (m, 1H), 8.05-8.27 (m, 1H), 7.59-7.74 (m, 1H), 7.15-7.32 (m, 2H), 6.78-6.98 (m, 2H), 5.89-6.00 (m, 1H), 4.92-5.10 (m, 1H), 4.32-4.46 (m, 1H), 4.22-4.32 (m, 1H), 3.76-3.98 (m, 2H), 3.57-3.71 (m, 2H), 2.98-3.04 (m, 1H), 1.26-1.32 (m, 6H); LC/MS [M+H]=682.8.

Example 175 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)phenyl)-2-(thiazol-4-yl)propanoic acid

Step 1:

A mixture of 1-(bromomethyl)-4-nitro-benzene (7.62 g, 35.26 mmol, 3 eq) and NaI (352.31 mg, 2.35 mmol, 0.2 eq) in DMF (50 mL) was stirred at 15° C. for 30 min. Then this mixture was added to a solution of ethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-6-ethynyl-2,2-dimethyltetrahydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)-2-(thiazol-4-yl)acetate (5 g, 11.75 mmol, 1 eq) and Cs₂CO₃ (19.15 g, 58.76 mmol, 5 eq) in DMF (50 mL) at 15° C. was stirred for 30 min. The resulting mixture was stirred for 8 h before it was quenched by water (200 mL). The mixture was extracted with EtOAc (4×30 mL). The combined organic layer was washed with water (3×100 mL), dried over anhydrous Na₂SO₄, filtered and concentrated. The residue was purified by flash column chromatography on silica gel (0-40% of EtOAc in petroleum ether) to provide ethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-6-ethynyl-2,2-dimethyl-tetrahydrofuro [2,3-d][1,3]dioxol-5-yl)methoxy)-3-(4-nitrophenyl)-2-(thiazol-4-yl)propanoate (4.89 g) as a syrup.

Step 2:

To a solution of ethyl 2-(((3aR,5R,6R,6aR)-6-acetoxy-6-ethynyl-2,2-dimethyltetra-hydrofuro[2,3-d][1,3]dioxol-5-yl)methoxy)-3-(4-nitrophenyl)-2-(thiazol-4-yl)propanoate (4.89 g, impure) in DCM (25 mL) and H₂O (2.5 mL) was added TFA (25 mL 337.65 mmol). The mixture was stirred at 30° C. for 23 h before it was diluted with water (100 mL) and the resulting mixture was extracted with DCM (6×30 mL). The combined organic layer was washed with saturated aq. NaHCO₃ (2×100 mL), dried over anhydrous Na₂SO₄, filtered and concentrated to provide crude ethyl 2-(((2R,3S,4R)-3-ethynyl-3,4,5-trihydroxytetrahydro-furan-2-yl)methoxy)-3-(4-nitrophenyl)-2-(thiazol-4-yl)propanoate (4.56 g) as a brown oil.

To a solution of crude ethyl 2-(((2R,3S,4R)-3-ethynyl-3,4,5-trihydroxytetrahydro-furan-2-yl)methoxy)-3-(4-nitrophenyl)-2-(thiazol-4-yl)propanoate (4.56 g) in DCM (50 mL) was added 4-DMAP (232.86 mg, 1.91 mmol), pyridine (6.15 mL, 76.24 mmol) and Ac₂O (8.93 mL, 95.30 mmol) dropwise. The mixture was stirred at 15° C. for 19 h before it was quenched with water (100 mL) and the resulting mixture was extracted with DCM (4×30 mL). The combined organic layer was washed with water (3×100 mL), and dried over anhydrous Na₂SO₄, filtered and concentrated. The crude residue was purified by flash column chromatography on silica gel (10-55% EtOAc in petroleum ether) to provide (3R,4R,5R)-5-(((1-ethoxy-3-(4-nitrophenyl)-1-oxo-2-(thiazol-4-yl)propan-2-yl)oxy)methyl)-4-ethynyltetrahydrofuran-2,3,4-triyl triacetate (1.02 g) as a yellow oil.

Step 3:

To a solution of 2,6-dichloro-9H-purine (382.64 mg, 2.02 mmol) in MeCN (5 mL) was added BSA (1.04 mL, 4.22 mmol). The suspension was stirred at 65° C. for 0.5 h as it became clear. The resulting solution was cooled down to 0° C. and followed by addition of a solution of (3R,4R,5R)-5-(((1-ethoxy-3-(4-nitrophenyl)-1-oxo-2-(thiazol-4-yl)propan-2-yl)oxy)methyl)-4-ethynyltetrahydrofuran-2,3,4-triyl triacetate (1.02 g) in MeCN (5 mL) and TMSOTf (4.22 mmol, 762.15 uL). Then the mixture was stirred at 65° C. for 1 h before it was quenched with saturated aq. NaHCO₃ (40 mL) and the resulting mixture was extracted EtOAc (4×20 mL). The combined organic layer was dried over anhydrous Na₂SO₄, filtered and concentrated to provide crude (2R,3R,4R,5R)-5-(2,6-dichloro-9H-purin-9-yl)-2-(((1-ethoxy-3-(4-nitrophenyl)-1-oxo-2-(thiazol-4-yl)propan-2-yl)oxy)methyl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate (1.71 g) as a yellow solid.

Step 4:

To a solution of crude (2R,3R,4R,5R)-5-(2,6-dichloro-9H-purin-9-yl)-2-(((1-ethoxy-3-(4-nitrophenyl)-1-oxo-2-(thiazol-4-yl)propan-2-yl)oxy)methyl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate (1.0 g) in MeOH (20 mL) in a seal tube was added NH₄·OH (28.04 mmol, 4.00 mL, 27% concentration). The mixture was sealed and stirred at 100° C. for 1.5 h before it was allowed to cool and diluted with water (20 mL) and the resulting mixture was extracted with EtOAc (3×10 mL). The combined organic layer was dried over anhydrous Na₂SO₄, filtered and concentrated to give crude ethyl 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-(4-nitrophenyl)-2-(thiazol-4-yl)propanoate (752 mg) as a yellow solid.

Step 5:

To a solution of crude ethyl 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-(4-nitrophenyl)-2-(thiazol-4-yl)-propanoate (752 mg), 4-DMAP (58.33 mg, 477.44 umol) and Et₃N (7.16 mmol, 996.81 uL) in DMF (8 mL) at 0° C. was added Boc₂O (1.04 g, 4.77 mmol). The mixture was stirred at 20° C. for 2 h before it was diluted with water (40 mL) and the resulting mixture was extracted with EtOAc (4×20 mL). The combined organic layer was dried over anhydrous Na₂SO₄, filtered and concentrated to give crude ethyl 2-(((2R,3R,4R,5R)-5-(6-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-4-((tert-butoxycarbonyl)oxy)-3-ethynyl-3-hydroxytetrahydrofuran-2-yl)methoxy)-3-(4-nitrophenyl)-2-(thiazol-4-yl)propanoate (911 mg) as a brown solid.

Step 6:

To a solution of crude ethyl 2-(((2R,3R,4R,5R)-5-(6-(bis-(tert-butoxycarbonyl)-amino)-2-chloro-9H-purin-9-yl)-4-((tert-butoxycarbonyl)oxy)-3-ethynyl-3-hydroxytetra-hydrofuran-2-yl)methoxy)-3-(4-nitrophenyl)-2-(thiazol-4-yl)propanoate (711 mg) in EtOH (7 mL) was added saturated aq. NH₄Cl (764.21 umol, 7 mL) and iron (426.77 mg, 7.64 mmol). The mixture was stirred at 50° C. for 2 h before it was filtered through a pad of Celite and the filtrate was concentrated. Then the crude residue was taken up in water (20 mL) and the resulting mixture was extracted with EtOAc (3×15 mL). The combined organic layer was dried over anhydrous Na₂SO₄, filtered and concentrated to give crude ethyl 3-(4-amino-phenyl)-2-(((2R,3R,4R,5R)-5-(6-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-4-((tert-butoxycarbonyl)oxy)-3-ethynyl-3-hydroxytetrahydrofuran-2-yl)methoxy)-2-(thiazol-4-yl)propanoate (552 mg) as a brown solid.

Step 7:

To a solution of crude ethyl 3-(4-aminophenyl)-2-(((2R,3R,4R,5R)-5-(6-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-4-((tert-butoxycarbonyl)oxy)-3-ethynyl-3-hydroxytetrahydrofuran-2-yl)methoxy)-2-(thiazol-4-yl)propanoate (552 mg) in DCM (5 mL) was added 1-chloro-3-isocyanato-propane (109.94 mg, 919.60 umol). The mixture was stirred at 15° C. for 16 h before it was concentrated under reduce pressure. The crude residue was purified by flash column chromatography on silica gel (20-100% EtOAc in petroleum ether) to provide ethyl 2-(((2R,3R,4R,5R)-5-(6-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-4-((tert-butoxycarbonyl)oxy)-3-ethynyl-3-hydroxytetrahydrofuran-2-yl)methoxy)-3-(4-(3-(3-chloropropyl)ureido)phenyl)-2-(thiazol-4-yl)propanoate (283 mg) as an off-white solid.

Step 8:

To a solution of ethyl 2-(((2R,3R,4R,5R)-5-(6-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-4-((tert-butoxycarbonyl)oxy)-3-ethynyl-3-hydroxytetrahydrofuran-2-yl)methoxy)-3-(4-(3-(3-chloropropyl)ureido)phenyl)-2-(thiazol-4-yl)propanoate (283 mg, 277.47 umol, 1 eq) in THF (3 mL) was added NaH (55.49 mg, 1.39 mmol, 60% in mineral oil, 5 eq). The mixture was stirred at 15° C. for 5 h before it was quenched with H₂O (1.5 mL). To this mixture was added NaOH (166.48 mg, 4.16 mmol, 15 eq) and the resulting mixture was stirred at 40° C. for 48 h before the organic volatile was removed under reduced pressure. The aq. layer was acidified with 2N aq. HCl (1 mL) and concentrated under reduced pressure to give crude 2-(((2R,3S,4R,5R)-5-(6-((tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)phenyl)-2-(thiazol-4-yl)propanoic acid (238 mg) as a yellow solid.

Step 9:

A mixture of crude 2-(((2R,3S,4R,5R)-5-(6-((tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-(4-(2-oxotetra-hydropyrimidin-1 (2H)-yl)phenyl)-2-(thiazol-4-yl)propanoic acid (238 mg) in DCM (2 mL) was added TFA (9.45 mmol, 0.7 mL). The mixture was stirred at 15° C. for 2 h before it was concentrated under reduced pressure. The crude residue was purified by Preparative HPLC ([water (0.225% FA)-ACN]; B %: 20%-40%, 10 min) to provide a diastereomeric mixture (ca. 1:1) of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetra-hydrofuran-2-yl)methoxy)-3-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)phenyl)-2-(thiazol-4-yl)propanoic acid (22.9 mg) as a white solid.

¹H NMR (400 MHz, CD₃OD) δ ppm 9.01 (m, 1H), 7.98-8.32 (m, 1H), 7.59-7.83 (m, 1H), 6.91-7.34 (m, 4H), 5.88-6.07 (m, 1H), 4.72-4.96 (m, 1H), 4.13-4.32 (m, 1H), 3.60-4.00 (m, 4H), 3.43-3.56 (m, 2H), 3.35-3.42 (m, 2H), 2.96-3.14 (m, 1H), 1.89-2.08 (m, 2H); LC/MS [M+H]=655.3.

Example 176 Synthesis of 2-(((2R,3S,4R,5R)-5-(2-chloro-6-(isopropylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)phenyl)-2-(thiazol-4-yl)propanoic acid

Step 1:

A solution of crude (2R,3R,4R,5R)-5-(2,6-dichloro-9H-purin-9-yl)-2-(((1-ethoxy-3-(4-nitrophenyl)-1-oxo-2-(thiazol-4-yl)propan-2-yl)oxy)methyl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate (1.17 g) in MeCN (10 mL) was added propan-2-amine (1.0 mL, 11.64 mmol) and DIEA (0.9 mL). The mixture was stirred at 15° C. for 16 h before it was diluted with water (30 mL) and the resulting mixture was extracted EtOAc (4×20 mL). The combined organic layer was dried over anhydrous Na₂SO₄, filtered and concentrated to give crude (2R,3R,4R,5R)-5-(2-chloro-6-(isopropylamino)-9H-purin-9-yl)-2-(((1-ethoxy-3-(4-nitrophenyl)-1-oxo-2-(thiazol-4-yl)propan-2-yl)oxy)methyl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate (1.16 g) as a yellow solid.

Step 2:

To a solution of crude (2R,3R,4R,5R)-5-(2-chloro-6-(isopropylamino)-9H-purin-9-yl)-2-(((1-ethoxy-3-(4-nitrophenyl)-1-oxo-2-(thiazol-4-yl)propan-2-yl)oxy)methyl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate (1.16 g) in EtOH (5 mL) was added Fe powder (856.75 mg, 15.34 mmol) and saturated aq. NH₄Cl (1.53 mmol, 5 mL). The mixture was stirred at 50° C. for 2 h before it was filtered through a pad of Celite and the filtrate was concentrated to give crude (2R,3R,4R,5R)-2-(((3-(4-aminophenyl)-1-ethoxy-1-oxo-2-(thiazol-4-yl)propan-2-yl)oxy)methyl)-5-(2-chloro-6-(isopropylamino)-9H-purin-9-yl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate (1.05 g) as a yellow solid.

Step 3:

To a solution of crude (2R,3R,4R,5R)-2-(((3-(4-aminophenyl)-1-ethoxy-1-oxo-2-(thiazol-4-yl)propan-2-yl)oxy)methyl)-5-(2-chloro-6-(isopropylamino)-9H-purin-9-yl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate (1.05 g) in DCM (10 mL) was added 1-chloro-3-isocyanato-propane (172.85 mg, 1.45 mmol). The mixture was stirred at 15° C. for 16 h before it was quenched with water (20 mL) and the resulting mixture was extracted with DCM (3×10 mL). The combined organic layer was dried over anhydrous Na₂SO₄, filtered and concentrated to give crude ethyl 2-(((2R,3S,4R,5R)-5-(2-chloro-6-(isopropylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-(4-(3-(3-chloropropyl)-ureido)phenyl)-2-(thiazol-4-yl)propanoate (1.33 g) as a yellow solid.

Step 4:

To a solution of crude ethyl 2-(((2R,3S,4R,5R)-5-(2-chloro-6-(isopropylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-(4-(3-(3-chloropropyl)-ureido)phenyl)-2-(thiazol-4-yl)propanoate (1.23 g) in THF (12 mL) was added NaH (290.84 mg, 7.27 mmol, 60% in mineral oil). The mixture was stirred at 15° C. for 5 h before it was quenched with H₂O (6 mL) and followed by addition of NaOH (290.85 mg, 7.27 mmol). The mixture was stirred at 15° C. for 16 h and then at 40° C. for 8 h. Additional NaOH (600 mg) was added to mixture and the mixture was stirred at 40° C. for 4 h before it was quenched with water (20 mL). The resulting solution was extracted with EtOAc (15 mL). The aq. layer was acidified with 2N aq. HCl (15 mL) to produce a precipitate. The solid was collected by filtration and purified by preparative HPLC (column: YMC-Actus Triart C18 150*30 mm*5 um; mobile phase: [water (0.225% FA)-ACN]; B %: 30%-50%, 10 min) to provide a diastereomeric mixture (ca. 1:1) of 2-(((2R,3S,4R,5R)-5-(2-chloro-6-(isopropyl-amino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-(4-(2-oxotetrahydropyrimidin-1 (2H)-yl)phenyl)-2-(thiazol-4-yl)propanoic acid (245 mg) as a white solid

¹H NMR (400 MHz, CD₃OD) δ ppm 8.99 (d, J=1.6 Hz, 1H), 7.88-8.18 (m, 1H), 7.53-7.79 (m, 1H), 7.30 (d, J=8.3 Hz, 1H), 7.03-7.13 (m, 2H), 6.95 (d, J=8.4 Hz, 1H), 5.83-6.03 (m, 1H), 4.63-4.74 (m, 1H), 4.33-4.43 (m, 1H), 4.09-4.29 (m, 1H), 3.72-4.01 (m, 3H), 3.59-3.70 (m, 1H), 3.41-3.53 (m, 2H), 3.33-3.38 (m, 2H), 2.91-3.14 (m, 1H), 1.83-2.05 (m, 2H), 1.25-1.35 (m, 6H); LC/MS [M+H]=697.4.

Example 177 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-chloro-4-(isopropylamino)-1H-pyrazolo[3,4-d]pyrimidin-1-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-phenyl-2-(thiazol-4-yl)propanoic acid

Step 1:

To a solution of 4,6-dichloro-1H-pyrazolo[3,4-d]pyrimidine (620 mg, 1.11 mmol, 1 eq) and (3R,4R,5R)-5-(((1-ethoxy-1-oxo-3-phenyl-2-(thiazol-4-yl)propan-2-yl)oxy)methyl)-4-ethynyltetrahydrofuran-2,3,4-triyl triacetate (230.35 mg, 1.22 mmol, 1.1 eq) in MeCN (6.5 mL) under a N₂ atmosphere at 0° C. was added DBU (501 uL, 3.32 mmol, 3 eq). The mixture was stirred at 0° C. for 5 min and followed by addition of TMSOTf (900.93 uL, 4.99 mmol, 4.5 eq) dropwise. The mixture was stirred at 0° C. for 30 min and then stirred at 65° C. for 16 h before it was quenched with saturated aq. NaHCO₃ (10 mL) and extracted with EtOAc (3×6 mL). The combined organic phase was dried over anhydrous Na₂SO₄, filtered and concentrated. The crude residue was purified by flash column chromatography on silica gel (10-40% of EtOAc in petroleum ether) to provide (2R,3R,4R,5R)-5-(4,6-dichloro-1H-pyrazolo[3,4-d]pyrimidin-1-yl)-2-(((1-ethoxy-1-oxo-3-phenyl-2-(thiazol-4-yl)propan-2-yl)oxy)methyl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate (220 mg) as a foam.

Step 2:

To (2R,3R,4R,5R)-5-(4,6-dichloro-1H-pyrazolo[3,4-d]pyrimidin-1-yl)-2-(((1-ethoxy-1-oxo-3-phenyl-2-(thiazol-4-yl)propan-2-yl)oxy)methyl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate (260 mg, 377.61 umol, 1 eq) in EtOH (2 mL) was added propan-2-amine (64.89 uL, 755.23 umol, 2 eq) and DIEA (131.55 uL, 755.23 umol, 2 eq). The mixture was stirred at 15° C. for 4 h before it was diluted with EtOAc (30 mL), washed with water (8 mL), brine (8 mL), dried over anhydrous Na₂SO₄, filtered and concentrated. The crude residue was purified by preparative TLC (EtOAc:petroleum ether=2:1) to give (2R,3R,4R,5R)-5-(6-chloro-4-(isopropylamino)-1H-pyrazolo[3,4-d]pyrimidin-1-yl)-2-(((1-ethoxy-1-oxo-3-phenyl-2-(thiazol-4-yl)propan-2-yl)oxy)methyl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate (70 mg) as a foam.

Step 3:

To a solution of (2R,3R,4R,5R)-5-(6-chloro-4-(isopropylamino)-1H-pyrazolo[3,4-d]pyrimidin-1-yl)-2-(((1-ethoxy-1-oxo-3-phenyl-2-(thiazol-4-yl)propan-2-yl)oxy)methyl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate (70 mg, 98.43 umol, 1 eq) in THF (1 mL) was added LiOH·H₂O (4.13 mg). The mixture was stirred at 50° C. for 14 h before it was concentrated to dryness. The crude residue was purified by preparative HPLC (column: YMC-Actus Triart C18 150*30 mm*5 um; mobile phase: [water (0.225% FA)−ACN]; B %: 43%-63%, 10 min) and dried by lyophilization to provide a diastereomeric mixture (ca. 1:1) of 2-(((2R,3S,4R,5R)-5-(6-chloro-4-(isopropylamino)-1H-pyrazolo[3,4-d]pyrimidin-1-yl)-3-ethynyl-3,4-dihydroxytetrahydro-furan-2-yl)methoxy)-3-phenyl-2-(thiazol-4-yl)propanoic acid (15.7 mg) as a white solid.

¹H NMR (400 MHz, CD₃OD) δ ppm 8.76-9.10 (m, 1H), 7.93-8.08 (m, 1H), 7.40-7.65 (m, 1H), 6.89-7.08 (m, 4H), 6.80-6.88 (m, 1H), 6.11-6.20 (m, 1H), 5.14-5.28 (m, 1H), 4.38-4.50 (m, 1H), 4.29-4.37 (m, 1H), 3.93-4.11 (m, 1H), 3.78-3.86 (m, 1H), 3.47-3.63 (m, 2H), 2.97-3.09 (m, 1H), 1.25-1.31 (m, 6H); LC/MS [M+H]=598.7.

Example 178 Synthesis of 2-(((2R,3S,4R,5R)-5-(4-amino-6-chloro-1H-pyrazolo[3,4-d]pyrimidin-1-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-phenyl-2-(thiazol-4-yl)propanoic acid

Step 1:

To a solution of (2R,3R,4R,5R)-5-(4,6-dichloro-1H-pyrazolo[3,4-d]pyrimidin-1-yl)-2-(((1-ethoxy-1-oxo-3-phenyl-2-(thiazol-4-yl)propan-2-yl)oxy)methyl)-3-ethynyltetrahydro-furan-3,4-diyl diacetate (100 mg, 145.24 umol, 1 eq) in THF (1 mL) was added NH₄OH (199.76 uL, 1.45 mmol, 10 eq). The mixture was stirred at 15° C. for 14 h before it was concentrated to dryness to provide crude (2R,3R,4R,5R)-5-(4-amino-6-chloro-1H-pyrazolo-[3,4-d]pyrimidin-1-yl)-2-(((1-ethoxy-1-oxo-3-phenyl-2-(thiazol-4-yl)propan-2-yl)oxy)-methyl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate (120 mg) as a white solid.

Step 2:

To a solution of crude (2R,3R,4R,5R)-5-(4-amino-6-chloro-1H-pyrazolo[3,4-d]pyrimidin-1-yl)-2-(((1-ethoxy-1-oxo-3-phenyl-2-(thiazol-4-yl)propan-2-yl)oxy)methyl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate (145.24 umol, 1 eq) in THF (4 mL) and H₂O (2 mL) was added LiOH·H₂O (60.94 mg, 1.45 mmol, 10 eq). The mixture was stirred at 50° C. for 16 h before it was concentrated to dryness. The crude residue was purified by preparative HPLC (column: YMC-Actus Triart C18 150*30 mm*5 um; mobile phase: [water (0.225% FA)-ACN]; B %: 28%-48%, 10 min) and dried by lyophilization to provide a diastereomeric mixture (ca. 1:1) of 2-(((2R,3S,4R,5R)-5-(4-amino-6-chloro-1H-pyrazolo[3,4-d]pyrimidin-1-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-phenyl-2-(thiazol-4-yl)-propanoic acid (32.8 mg) as a white solid.

¹H NMR (400 MHz, CD₃OD) δ ppm 8.87-9.01 (m, 1H), 7.91-8.06 (m, 1H), 7.47-7.67 (m, 1H), 7.01-7.06 (m, 2H), 6.93-7.00 (m, 2H), 6.84-6.90 (m, 1H), 6.12-6.20 (m, 1H), 5.14-5.27 (m, 1H), 4.26-4.33 (m, 1H), 3.76-4.03 (m, 2H), 3.48-3.70 (m, 2H), 2.96-3.05 (m, 1H); LC/MS [M+H]=557.0.

Example 179 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(thiazol-4-yl)acetic acid

Step 1:

To a solution of (2R,3R,4R,5R)-5-((6-N,N′-bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyl-2-(hydroxymethyl)tetrahydrofuran-3,4-diyl diacetate (2 g, 3.28 mmol) in toluene (10 mL) was added ethyl 2-diazo-2-(thiazol-4-yl)acetate (841 mg, 4.26 mmol) and Rh₂(OAc)₄ (145 mg, 0.328 mmol) under an argon atmosphere. The resulting mixture was stirred at 70° C. for 2 h before it was allowed to cool to room temperature. The organic volatile was removed under reduced pressure. The resulting crude was purified by silica gel column chromatography (0-40% EtOAc in hexanes) to provide (2R,3R,4R,5R)-5-(6-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-2-((2-ethoxy-2-oxo-1-(thiazol-4-yl)ethoxy)methyl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate (1.78 g) as a syrup.

Step 2:

To a solution of (2R,3R,4R,5R)-5-(6-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-2-((2-ethoxy-2-oxo-1-(thiazol-4-yl)ethoxy)methyl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate (310 mg) in DCM (3 mL) at 25° C. was added TFA (2 mL). The mixture was stirred for 2 h before it was concentrated under reduced pressure to provide crude (2R,3R,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-2-((2-ethoxy-2-oxo-1-(thiazol-4-yl)ethoxy)methyl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate.

To a solution of crude (2R,3R,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-2-((2-ethoxy-2-oxo-1-(thiazol-4-yl)ethoxy)methyl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate in THF (1 mL) and H₂O (1 mL) at 0° C. was added LiOH monohydrate (100 mg). The resulting mixture was stirred at 25° C. overnight before the organic volatile was removed under reduced pressure. The mixture was cooled to 0° C. before it was acidified to pH˜6 with 1N aq. HCl solution and concentrated under reduced pressure. The crude residue was purified by preparative reversed-phase HPLC to provide a diastereomeric mixture (ca. 1:1) of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydro-furan-2-yl)methoxy)-2-(thiazol-4-yl)acetic acid as a white solid.

¹H NMR (CD₃OD, 300 MHz) δ 8.84-9.00 (m, 2H), 7.67-7.68 (m, 1H), 6.02-6.06 (m, 1H), 5.28-5.32 (d, J=12.27 Hz, 1.5H), 5.14-5.16 (d, J=7.56 Hz, 0.5H), 4.24-4.28 (m, 1H), 3.69-4.09 (m, 2H), 3.16 (s, 0.5H), 2.95 (s, 0.5H); LC/MS [M+H]=467.0.

Examples 180 and 181 Synthesis of (S)-2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-phenyl-2-(thiazol-4-yl)propanoic acid and (R)-2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-phenyl-2-(thiazol-4-yl)propanoic acid

Proceeding as described in Example 169 above but substituting 3-(bromomethyl)thiophene and 2-chloro-N-isopropyl-9purin-6-amine with benzyl bromide and 2-chloroadenine provided a pair of diastereomeric products which the stereo configuration was assigned arbitrarily. Both products were purified by preparative HPLC and isolated as white solids.

(S)-2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetra-hydrofuran-2-yl)methoxy)-3-phenyl-2-(thiazol-4-yl)propanoic acid: ¹H NMR (CD₃OD, 300 MHz) δ 8.95-8.96 (d, J=2.01 Hz, 1H), 8.34 (s, 1H), 7.54-7.55 (d, J=2.01 Hz, 1H), 6.97-7.12 (m, 5H), 5.97-5.99 (d, J=6.99 Hz, 1H), 4.97-4.99 (d, J=7.08 Hz, 1H), 4.27-4.29 (t, J=4.23, 3.18 Hz, 1H), 3.88-3.99 (m, 2H), 3.62-3.79 (q, J=14.82, 39.24 Hz, 2H), 2.97 (s, 1H); LC/MS [M+H]=557.0.

(R)-2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetra-hydrofuran-2-yl)methoxy)-3-phenyl-2-(thiazol-4-yl)propanoic acid: ¹H NMR (CD₃OD, 300 MHz) δ 8.95-8.96 (m, 1H), 7.99 (s, 1H), 7.70-7.71 (d, J=1.98 Hz, 1H), 7.05-7.25 (m, 5H), 5.92-5.94 (d, J=7.02 Hz, 1H), 4.85-4.87 (d, J=7.29 Hz, 1H), 4.20-4.22 (q, J=2.64 Hz, 1H), 3.58-3.90 (m, 4H), 3.02 (s, 1H); LC/MS [M+H]=557.0.

Example 182 Synthesis of 3-(2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-carboxy-2-(thiazol-4-yl)ethyl)benzoic acid

Proceeding as described in Example 179 above but substituting BnBr with methyl 3-(bromomethyl)benzoate provided the title compound as a mixture of diastereomers (ca. 1:1) and isolated as a white solid.

¹H NMR (CD₃OD, 300 MHz) δ 8.99-9.01 (m, 1H), 8.33 (s, 0.5H), 8.14 (s, 0.5H), 7.66-7.88 (m, 3H), 7.45-7.48 (d, J=7.29 Hz, 0.5H), 7.36-7.39 (d, J=7.86 Hz, 0.5H), 7.17-7.22 (t, J=7.56 Hz, 0.5H), 7.00-7.05 (d, J=7.47 Hz, 0.5H), 5.99-6.01 (d, J=7.29 Hz, 0.5H), 5.93-5.95 (d, J=6.87 Hz, 0.5H), 5.00-5.03 (d, J=7.38 Hz, 0.5H), 4.90-4.95 (d, J=6.80 Hz, 0.5H), 4.23-4.31 (m, 1H), 3.80-4.01 (m, 2H), 3.63-3.69 (m, 2H), 3.01 (s, 0.5H), 2.92 (s, 0.5H); LC/MS [M+H]=601.0.

Example 183 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(thiazol-4-yl)-3-(3-(trifluoromethoxy)phenyl)propanoic acid

Proceeding as described in Example 179 above but substituting BnBr with 1-(bromomethyl)-3-(trifluoromethoxy)benzene provided the title compound as a mixture of diastereomers (ca. 1:1) and isolated as a white solid.

¹H NMR (CD₃OD, 300 MHz) δ 8.97-9.00 (m, 1H), 8.41 (s, 0.5H), 8.26 (s, 0.5H), 7.68-7.69 (d, J=1.92 Hz, 0.5H), 7.62-7.63 (d, J=1.83 Hz, 0.5H), 6.88-7.21 (m, 4H), 6.00-6.02 (d, J=7.14 Hz, 0.5H), 5.94-5.96 (d, J=6.78 Hz, 0.5H), 5.04-5.07 (d, J=7.44 Hz, 0.5H), 4.91-4.94 (d, J=6.87 Hz, 0.5H), 4.28-4.33 (m, 1H), 3.62-3.96 (m, 4H), 2.98 (s, 0.5H), 2.96 (s, 0.5H); LC/MS [M+H]=641.0.

Example 184 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(thiazol-4-yl)pent-4-ynoic acid

Proceeding as described in Example 179 above but substituting BnBr with propargyl bromide provided the title compound as a mixture of diastereomers (ca. 1:1) and isolated as a white solid.

¹H NMR (CD₃OD, 300 MHz) δ 8.95 (s, 1H), 8.79-8.83 (d, J=13.95 Hz, 1H), 7.73 (s, 1H), 6.04-6.06 (d, J=7.05 Hz, 1H), 4.97-5.05 (dd, J=7.29, 17.91 Hz, 1H), 4.24-4.30 (m, 1H), 3.69-3.94 (m, 2H), 3.34-3.38 (m, 2H), 3.04 (s, 0.5H), 2.93 (s, 0.5H), 2.22-2.30 (dt, J=1.74, 19.62 Hz, 1H); LC/MS [M+H]=505.0.

Examples 185 and 186 Synthesis of (S)-2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-N-hydroxy-2-(thiazol-4-yl)acetamide and (S)-2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-N-hydroxy-2-(thiazol-4-yl)acetamide

To a solution of (2R,3R,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-2-((2-ethoxy-2-oxo-1-(thiazol-4-yl)ethoxy)methyl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate (2 g, 3.45 mmole) in MeOH (20 mL) was added 50% NH₂OH in H₂O (30 mL). The reaction mixture was stirred at 40° C. for 1 h before it was concentrated under reduced pressure. The crude residue was purified by preparative reversed-phase HPLC to provide a pair of diastereomeric title products which the stereo configuration was assigned arbitrarily. Both products were isolated as white solids.

(S)-2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetra-hydrofuran-2-yl)methoxy)-N-hydroxy-2-(thiazol-4-yl)acetamide: ¹H NMR (CD₃OD, 300 MHz) δ 9.02-9.03 (d, J=1.77 Hz, 1H), 8.45 (s, 1H), 7.68-7.69 (d, J=1.8 Hz, 1H), 5.98-6.01 (d, J=6.96 Hz, 1H), 4.92-4.95 (d, J=6.93 Hz, 1H), 4.29-4.32 (q, J=2.82, 2.28 Hz, 1H), 3.91-4.10 (m, 2H), 3.18 (s, 1H); LC/MS [M+H]=482.0.

(R)-2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetra-hydrofuran-2-yl)methoxy)-N-hydroxy-2-(thiazol-4-yl)acetamide: ¹H NMR (CD₃OD, 300 MHz) δ 8.97 (s, 1H), 8.46 (s, 1H), 7.68 (s, 1H), 5.97-6.00 (d, J=6.96 Hz, 1H), 4.88-4.90 (d, J=6.93 Hz, 1H), 4.33-4.35 (m, 1H), 3.96-4.08 (m, 2H), 3.12 (s, 1H); LC/MS [M+H]=482.0.

Examples 187 and 188 Synthesis of (S)-2-(((2R,3S,4R,5R)-5-(2-chloro-6-(methylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-phenyl-2-(thiazol-4-yl)propanoic acid and (R)-2-(((2R,3S,4R,5R)-5-(2-chloro-6-(methylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-phenyl-2-(thiazol-4-yl)propanoic acid

Example 187 Example 188

Proceeding as described in Examples 170 and 171 above but substituting 2-chloro-N-isopropyl-9H-purin-6-amine with 2-chloro-N-methyl-9H-purin-6-amine provided the title compounds as a pair of diastereomers (ca. 1:1) and isolated as white solids.

(S)-2-(((2R,3S,4R,5R)-5-(2-chloro-6-(methylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxy-tetrahydrofuran-2-yl)methoxy)-3-phenyl-2-(thiazol-4-yl)propanoic acid: ¹H NMR (CD₃OD, 300 MHz) δ 8.99 (s, 1H), 7.97 (s, 1H), 7.69 (s, 1H), 7.08-7.22 (m, 5H), 5.93-5.95 (d, J=6.9 Hz, 1H), 4.96-4.98 (d, J=6.0 Hz, 1H), 3.59-4.22 (m, 5H), 3.01-3.06 (m, 4H); LC/MS [M+H]=571.0.

(R)-2-(((2R,3S,4R,5R)-5-(2-chloro-6-(methylamino)-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-phenyl-2-(thiazol-4-yl)propanoic acid: ¹H NMR (CD₃OD, 300 MHz) δ 8.97-8.98 (d, J=1.83 Hz, 1H), 8.15 (s, 1H), 7.58-7.59 (d, J=1.77 Hz, 1H), 6.94-7.09 (m, 5H), 5.98-6.00 (d, J=7.17 Hz, 1H), 4.98-5.01 (d, J=7.26 Hz, 1H), 4.27-4.29 (t, J=3.48 Hz, 1H), 3.93 (m, 2H), 3.58-3.80 (q, J=14.46, 38.7 Hz, 2H), 3.07 (s, 3H), 2.94 (s, 1H); LC/MS [M+H]=571.0.

Examples 189 and 190 Synthesis of (S)-2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-cyano-3-phenylpropanoic acid and (R)-2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-cyano-3-phenylpropanoic acid

Step 1:

To a solution of R,3R,4R,5R)-5-(6-N,N′-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyl-2-(hydroxymethyl)tetrahydrofuran-3,4-diyl diacetate (510 mg, 0.836 mmol) in toluene (5 mL) was added ethyl 2-cyano-2-diazoacetate (134 mg, 0.961 mmol). The mixture was concentrated in vacuo. The mixture was taken up in dry toluene (2 mL) and followed by addition of Rh₂(OAc)₄ (8 mg, 17 umol) under argon atmosphere. The material was stirred and heated at 80° C. for 30 minutes before additional ethyl 2-cyano-2-diazoacetate (254 mg, 1.82 mmol) was added over 60 min at 80° C. The reaction was further heated at 80° C. for 80 minutes before it was cooled to room temperature and concentrated. The crude product was purified by CombiFlash silica gel chromatography (5-65% of EtOAc in hexanes) to provide a diastereomeric mixture of (2R,3R,4R,5R)-5-(6-N,N′-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-2-((1-cyano-2-ethoxy-2-oxoethoxy)methyl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate (230 mg, 38% yield) as an off-white foam.

Step 2:

An oven dried flask was charged with ((2R,3R,4R,5R)-5-(6-N,N′-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-2-((1-cyano-2-ethoxy-2-oxoethoxy)methyl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate (230 mg, 0.319 mmol) and taken up in dry DMF (4 mL). To this mixture was added Cs₂CO₃ (208 mg, 0.639 mmol) and followed by the addition of benzyl bromide (109 mg, 0.639 mmol). The mixture was stirred at 25° C. for 30 minutes before it was diluted with cold saturated aqueous NH₄Cl (40 mL) and extracted with EtOAc (40 mL). The aqueous phases were extracted with EtOAc (2×40 mL). The combined organic layer was dried over Na₂SO₄, filtered and concentrated. The crude product was purified by CombiFlash silica gel column chromatography (10-70% EtOAc in hexanes) to provide (2R,3R,4R,5R)-5-(6-N,N′-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-2-(((2-cyano-1-ethoxy-1-oxo-3-phenylpropan-2-yl)oxy)methyl)-3-ethynyltetrahydro-furan-3,4-diyl diacetate as a pair of diastereomers (215 mg, 83% yield) as an off-white solid.

Step 3:

A solution (2R,3R,4R,5R)-5-(6-N,N′-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-2-(((2-cyano-1-ethoxy-1-oxo-3-phenylpropan-2-yl)oxy)methyl)-3-ethynyltetra-hydrofuran-3,4-diyl diacetate (215 mg, 0.265 mmol) in a solution of TFA (1 mL) in DCM (1 mL) was stirred for 2 h before it was concentrated under reduced pressure. The residue was azetroped with DCM (8×8 mL) under reduced pressure. The residue was taken up in a mixture of MeOH in H₂O (2.2 mL, 5:1=v:v) and followed by addition of LiOH·H₂O (77 mg, 1.86 mmol, 7 eq) and THF (0.5 mL). The mixture was stirred at ambient temperature for 40 minutes before it was concentrated to dryness. The residue was dissolved in H₂O (15 mL). The aqueous phase was extracted with EtOAc (2×10 mL). The aqueous phase was acidified to pH 2.5 with 1N aq. HCl solution. The aqueous phase was extracted with EtOAc (3×50 mL). The combined organic layer was washed with brine (50 mL), dried over Na₂SO₄, filtered and concentrated. The crude residue was purified by preparative reversed-phase HPLC to provide the title compounds as a pair of diastereomers: (S)-2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-cyano-3-phenylpropanoic acid (33.7 mg, 26% yield) and (R)-2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-cyano-3-phenylpropanoic acid (30 mg, 23% yield) which the stereo configuration was assigned arbitrarily. Both were isolated as off-white solids.

(S)-2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetra-hydrofuran-2-yl)methoxy)-2-cyano-3-phenylpropanoic acid: ¹H NMR (CD₃OD, 300 MHz) δ 8.32 (bs, 1H), 7.20-7.36 (m, 5H), 6.02 (d, J=7.00 Hz, 1H), 4.68 (d, J=7.02 Hz, 1H), 4.33-4.37 (m, 1H), 4.18 (dd, J=9.91, 3.96 Hz, 1H), 3.99 (dd, J=9.94, 2.19 Hz, 1H), 3.41 (bs, 2H), 3.03 (s, 1H); LC/MS [M+H]=499.1.

(R)-2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetra-hydrofuran-2-yl)methoxy)-2-cyano-3-phenylpropanoic acid: ¹H NMR (CD₃OD, 300 MHz) δ 8.04 (bs, 1H), 7.21-7.39 (m, 5H), 5.99 (d, J=6.90 Hz, 1H), 4.79 (d, J=6.93 Hz, 1H), 4.31-4.36 (m, 1H), 4.19 (dd, J=10.07, 4.34 Hz, 1H), 4.12 (dd, J=10.10, 3.30 Hz, 1H), 3.38-3.44 (m, 2H), 3.09 (s, 1H); LC/MS [M+H]=499.1.

Examples 191 and 192 Synthesis of (S)-2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-phenyl-2-(1H-tetrazol-5-yl)propanoic acid and (R)-2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-phenyl-2-(1H-tetrazol-5-yl)propanoic acid

Step 1:

To a solution of ethyl 1H-tetrazole-5-acetate (3 g, 19.21 mmol) in DMF (40 mL) under argon atmosphere at 25° C. was added 2-(trimethylsilyl)ethoxymethyl chloride (4.1 mL, 23.05 mmol) and powdered potassium carbonate (5.31 g, 38.42 mmol). The reaction mixture was stirred overnight before it was diluted with brine (70 mL) and EtOAc (70 mL). The aqueous phase was extracted with EtOAc (2×70 mL). The combined organic layer was washed with brine (70 mL) and water (70 mL), dried over Na₂SO₄ and concentrated. The residue was purified by silica gel column chromatography (15-48% EtOAc in hexanes) to provide ethyl 2-(2-((2-(trimethylsilyl)ethoxy)methyl)-2H-tetrazol-5-yl)acetate (2.379 g) as a light yellow oil.

Step 2:

To a solution of ethyl 2-(2-((2-(trimethylsilyl)ethoxy)methyl)-2H-tetrazol-5-yl)acetate (2.379 g, 8.31 mmol) in dry acetonitrile (25 mL) under argon atmosphere was added DBU (1.87 mL, 12.47 mmol). To this mixture was added 4-acetamidobenzenesulfonyl azide (2.395 g, 9.96 mmol) in 3 equal portions over 5 minutes. The reaction mixture was stirred for 3.5 h the organic volatile was removed under reduced pressure. The residue was purified by silica gel column chromatography (20% EtOAc in hexanes) to provide ethyl 2-diazo-2-(2-((2-(trimethylsilyl)ethoxy)methyl)-2H-tetrazol-5-yl)acetate (2.316 g) as an oil.

Step 3:

To a solution of (2R,3R,4R,5R)-5-(6-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyl-2-(hydroxymethyl)tetrahydrofuran-3,4-diyl diacetate (2 g, 3.28 mmol) in toluene (8 mL) at 20° C. under N₂ atmosphere was added Rh₂(OAc)₄ (29 mg, 0.066 mmol, 0.066 eq) and ethyl 2-diazo-2-(2-((2-(trimethylsilyl)ethoxy)-methyl)-2H-tetrazol-5-yl)acetate (1.08 g, 3.44 mmol, 1.05 eq). The mixture was stirred at 75° C. for 1 h before additional ethyl 2-diazo-2-(2-((2-(trimethylsilyl)ethoxy)methyl)-2H-tetrazol-5-yl)acetate (720 mg) was added over 80 min. The reaction mixture was cooled to ambient temperature and concentrated. The crude material was purified by Combi-Flash silica gel column (5-80% EtOAc in hexanes) to provide a diastereomeric mixture of (2R,3R,4R,5R)-5-(6-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-2-((2-ethoxy-2-oxo-1-(2-((2-(trimethylsilyl)ethoxy)methyl)-2H-tetrazol-5-yl)ethoxy)methyl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate (1.608 g) as a gum.

Step 4:

To a solution of (2R,3R,4R,5R)-5-(6-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-2-((2-ethoxy-2-oxo-1-(2-((2-(trimethylsilyl)ethoxy)methyl)-2H-tetrazol-5-yl)ethoxy)methyl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate (1.555 g, 1.739 mmol) in dry toluene (10 mL). The mixture was concentrated under reduced pressure. The residue was taken up in dry DMF (10 mL) and followed by addition of benzyl bromide (1.189 g, 6.96 mmol) and dried Cs₂CO₃ (1.133 g, 3.478 mmol). The mixture was stirred at 25° C. for 5.5 h before it was diluted with saturated aq. NH₄Cl solution (60 mL). The aqueous phase was extracted with EtOAc (3×60 mL). The combined organic layer was washed with brine (60 mL), dried over Na₂SO₄, filtered and concentrated. The crude product was purified by flash silica gel column chromatography (5-65% EtOAc in hexanes) to provide a diastereomeric mixture of (2R,3R,4R,5R)-5-(6-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-2-(((1-ethoxy-1-oxo-3-phenyl-2-(2-((2-(trimethylsilyl)ethoxy)methyl)-2H-tetrazol-5-yl)propan-2-yl)oxy)methyl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate (1.041 g) as a foam.

Step 5:

To a solution of (2R,3R,4R,5R)-5-(6-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-2-(((1-ethoxy-1-oxo-3-phenyl-2-(2-((2-(trimethylsilyl)ethoxy)methyl)-2H-tetrazol-5-yl)propan-2-yl)oxy)methyl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate (1.041 g, 1.057 mmol) in a mixture of MeOH and H₂O (12 mL, 6:1=v:v) was added powdered LiOH·H₂O (349 mg, 8.5 mmol). The mixture was stirred at 23° C. for 16 h before it was concentrated to dryness. The residue was dissolved in H₂O (40 mL) and it was extracted with EtOAc (40 mL). The aqueous phase was acidified to pH 2.5 with 1N aq. HCl solution and extracted with EtOAc (3×40 mL). The combined organic layer was washed with brine (40 mL), dried over Na₂SO₄, filtered and concentrated to provide a diastereomeric mixture of 2-(((2R,3S,4R,5R)-5-(6-((tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-phenyl-2-(2-((2-(trimethylsilyl)ethoxy)methyl)-2H-tetrazol-5-yl)propanoic acid (784 mg) as an oil.

Step 6:

To a solution of 2-(((2R,3S,4R,5R)-5-(6-((tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-phenyl-2-(2-((2-(trimethylsilyl)ethoxy)methyl)-2H-tetrazol-5-yl)propanoic acid (138 mg, 0.179 mmol) in DCM (0.9 mL) under argon atmosphere at 0° C. was added TFA (0.9 mL). The mixture was stirred at 0° C. for 5 h and then stirred to ambient for 15 min before the organic volatile was removed under the reduced pressure. The residue was azetroped with DCM (3×15 mL) under reduced pressure. The crude residue was purified by preparative reversed-phase HPLC to provide the two title products as a pair of diastereomers: (S)-2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-phenyl-2-(1H-tetrazol-5-yl)propanoic from the first fraction and (R)-2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-3-phenyl-2-(1H-tetrazol-5-yl)propanoic acid from the later fraction. Both isolated as off-white solids.

(S)-2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetra-hydrofuran-2-yl)methoxy)-3-phenyl-2-(1H-tetrazol-5-yl)propanoic acid: ¹H NMR (CD₃OD, 300 MHz); δ 8.37 (s, 1H), 7.11-7.23 (m, 5H), 5.96 (d, J=6.57 Hz, 1H), 4.81 (d, J=6.57 Hz, 1H), 4.25-4.30 (m, 1H), 4.01 (dd, J=10.19, 2.29 Hz, 1H), 3.78 (d, J=13.90 Hz, 1H), 3.67 (d, J=13.90 Hz 1H), 3.72-3.79 (m, 1H), 3.06 (s, 1H); LC/MS [M+H]=542.2.

(R)-2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetra-hydrofuran-2-yl)methoxy)-3-phenyl-2-(1H-tetrazol-5-yl)propanoic acid: ¹H NMR (CD₃OD, 300 MHz); δ 8.37 (s, 1H), 6.92-7.11 (m, 5H), 6.01 (d, J=7.11 Hz, 1H), 5.06 (d, J=7.11 Hz, 1H), 4.35-4.39 (m, 1H), 4.11 (dd, J=10.06, 2.52 Hz, 1H), 4.01 (dd, J=10.06, 5.49 Hz, 1H), 3.80 (d, J=14.75 Hz 1H), 3.67 (d, J=14.75 Hz 1H), 2.96 (s, 1H); LC/MS [M+H]=542.2.

Examples 193 and 194 Synthesis of (S)-2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(2-phenylthiazol-4-yl)acetic acid and (R)-2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(2-phenylthiazol-4-yl)acetic acid

Proceeding as described in Example 179 but substituting ethyl 2-diazo-2-(thiazol-4-yl)acetate with ethyl (2-phenylthiazol-4-yl)diazoacetate which was prepared via the procedure described by Lefebvre, Quentin, et al., (Chemical Communications 2014, 50, 6617-6619) provided the title compounds as a pair of diastereomers (ca. 1:1). The stereo configuration was assigned arbitrarily. Both were isolated as off-white solids.

(S)-2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetra-hydrofuran-2-yl)methoxy)-2-(2-phenylthiazol-4-yl)acetic acid: ¹H NMR (CD₃OD, 300 MHz); δ 9.03 (bs, 1H), 7.91-7.97 (m, 2H), 7.60 (s, 1H), 7.39-7.45 (m, 3H), 6.06 (d, J=7.45 Hz, 1H), 5.28 (s, 1H), 4.92 (d, J=7.45 Hz, 1H), 4.29-4.33 (m, 1H), 4.12 (dd, J=10.45, 2.51 Hz, 1H), 4.01 (dd, J=10.46, 2.56 Hz, 1H), 2.92 (s, 1H); LC/MS [M+H]=543.1.

(R)-2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetra-hydrofuran-2-yl)methoxy)-2-(2-phenylthiazol-4-yl)acetic acid: ¹H NMR (CD₃OD, 300 MHz); δ 9.15 (s, 1H), 7.90-7.96 (m, 2H), 7.61 (s, 1H), 7.38-7.44 (m, 3H), 6.09 (d, J=7.48 Hz, 1H), 5.23 (d, J=7.48 Hz, 1H), 5.30 (s, 1H), 4.26-4.29 (m, 1H), 3.93 (dd, J=10.67, 2.18 Hz, 1H), 3.76 (dd, J=10.64, 2.48 Hz, 1H), 3.17 (s, 1H); LC/MS [M+H]=543.2.

Example 195 Synthesis of 4-((((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)(carboxy)methyl)thiazole-2-carboxylic acid

Step 1:

To a microwave vial was charged with ethyl thiooxamate (1.91 g, 14.36 mmol) and ethyl 4-bromoacetoacetate (3 g, 14.36 mmol) in dry toluene (27 mL). The mixture was irradiated in a microwave reactor at 90° C. for 1 hour. The reaction mixture was cooled to ambient and the solvent decanted and then was concentrated. The crude residue was purified by CombiFlash silica gel chromatography (2-56% EtOAc in hexanes) to provide ethyl 4-(2-ethoxy-2-oxoethyl)thiazole-2-carboxylate (890 mg, 26% yield) as a thick oil.

Step 2:

To a solution of ethyl 4-(2-ethoxy-2-oxoethyl)thiazole-2-carboxylate (890 mg, 3.66 mmol) in dry acetonitrile (12 mL) under argon atmosphere was added DBU (0.82 mL, 5.49 mmol) and 4-acetamidobenzenesulfonyl azide (1.055 g, 4.39 mmol). The reaction mixture was stirred for 1.5 hours before it was concentrated under reduced pressure. The residue was purified by silica gel column chromatography (20% EtOAc in hexanes) to provide ethyl 4-(1-diazo-2-ethoxy-2-oxoethyl)thiazole-2-carboxylate (894 mg, 90% yield) as a yellowish solid.

Step 3:

Proceeding as described in Example 179 but substituting ethyl 2-diazo-2-(thiazol-4-yl)acetate with ethyl 4-(1-diazo-2-ethoxy-2-oxoethyl)thiazole-2-carboxylate provided the title compound as a mixture of diastereomers (ca. 1:1) and isolated as off-white solids.

Isomer 1: ¹H NMR (CD₃OD, 300 MHz): δ 8.93 (s, 1H), 7.91 (s, 1H), 6.06 (d, J=7.42 Hz, 1H), 5.39 (s, 1H), 5.13 (d, J=7.42 Hz, 1H), 4.24-4.31 (m, 1H), 4.03-4.09 (m, 1H), 3.75-3.83 (m, 1H), 2.95 (s, 1H); LC/MS [M+H]=511.1.

Isomer 2: ¹H NMR (CD₃OD, 300 MHz): δ 8.87 (s, 1H), 7.93 (s, 1H), 6.04 (d, J=7.42 Hz, 1H), 5.33 (s, 1H), 4.91 (d, J=7.45 Hz, 1H), 4.24-4.31 (m, 1H), 3.92-4.01 (m, 2H), 3.19 (s, 1H); LC/MS [M+H]=511.1.

Example 196 Synthesis of 4-(1-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-1-carboxy-2-phenylethyl)thiazole-2-carboxylic acid

Proceeding as described in Example 179 above but substituting (2R,3R,4R,5R)-5-(6-N,N′-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyl-2-(hydroxyl-methyl)tetrahydrofuran-3,4-diyl diacetate with (2R,3R,4R,5R)-5-(6-N,N′-(bis-(tert-butoxy-carbonyl)amino))-2-chloro-9H-purin-9-yl)-2-((2-ethoxy-1-(2-(ethoxycarbonyl)thiazol-4-yl)-2-oxoethoxy)methyl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate provided the title compound as a mixture of diastereomers (ca. 1:1) and isolated as an off-white solid.

Isomer 1: ¹H NMR (CD₃OD, 300 MHz): δ 8.17 (bs, 1H), 7.81 (s, 1H), 6.92-7.25 (m, 5H), 5.95 (d, J=7.02 Hz, 1H), 4.89 (d, J=7.02 Hz, 1H), 4.29-4.34 (m, 1H), 3.59-4.05 (m, 4H), 3.01 (s, 1H); LC/MS [M+H]=601.1.

Isomer 2: ¹H NMR (CD₃OD, 300 MHz): δ 8.05 (bs, 1H), 7.90 (s, 1H), 6.92-7.25 (m, 5H), 6.00 (d, J=7.41 Hz, 1H), 5.04 (d, J=7.42 Hz, 1H), 4.21-4.26 (m, 1H), 3.59-4.05 (m, 4H), 3.06 (s, 1H); LC/MS [M+H]=601.1.

Examples 197 Synthesis of 2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)-2-(4-(2-aminopyridin-3-yl)benzyl)malonic acid

Proceeding as described in Example 22 above but substituting (2-oxo-1,2-dihydropyridin-3-yl)boronic acid with 3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)pyridin-2-amine provided the title compound as a white solid.

¹H NMR (CD₃OD, 300 MHz) δ 8.43 (s, 1H), 7.85-7.87 (dd, J=1.5, 6.42 Hz, 1H), 7.65-7.68 (dd, J=1.53, 7.38 Hz, 1H), 7.37-7.40 (d, J=8.13 Hz, 2H), 7.09-7.12 (d, J=8.07 Hz, 2H), 6.88-6.93 (t, J=6.9 Hz, 1H), 5.99-6.01 (d, J=6.72 Hz, 1H), 4.77-4.79 (d, J=7.0, 1H), 4.37-4.40 (m, 1H), 3.98-4.12 (m, 2H), 3.34-3.42 (m, 2H), 3.09 (s, 1H); LC/MS [M+H]=610.1.

Examples 198 & 199 Synthesis of (S)-3-([1,1′-biphenyl]-4-yl)-2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3,4-dihydroxy-3-methyltetrahydrofuran-2-yl)methoxy)-2-(thiazol-4-yl)propanoic acid and (R)-3-([1,1′-biphenyl]-4-yl)-2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3,4-dihydroxy-3-methyltetrahydrofuran-2-yl)methoxy)-2-(thiazol-4-yl)propanoic acid

Proceeding as described in Example 1 above but substituting (2R,3R,4R,5R)-5-(6-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-2-(((tert-butyldiphenylsilyl)oxy)-methyl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate and diethyl 2-diazomalonate with (2R,3R,4R,5R)-5-(6-(N,N′-bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-2-(hydroxylmethyl)-3-methyltetrahydrofuran-3,4-diyl diacetate and methyl 2-diazo-2-(thiazol-4-yl)acetate provided a pair of diastereomeric title products (ca. 1:1) which the stereo configuration was assigned arbitrarily. Both products were purified by preparative HPLC and isolated as white solids.

(S)-3-([1,1′-biphenyl]-4-yl)-2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3,4-dihydroxy-3-methyltetrahydrofuran-2-yl)methoxy)-2-(thiazol-4-yl)propanoic acid: ¹H NMR (CD₃OD, 300 MHz) δ 9.04 (s, 1H), 8.42 (s, 1H), 7.74 (s, 1H), 7.21-7.45 (m, 9H), 6.00-6.03 (d, J=8 Hz, 1H), 4.67-4.70 (d, J=7 Hz, 1H), 4.13 (s, 1H), 3.88-3.85 (m, 2H), 3.62-3.66 (d, J=14 Hz, 1H), 3.44-3.47 (d, J=11 Hz, 1H), 1.37 (s, 3H); LC/MS [M+H]=623.2.

(R)-3-([1,1′-biphenyl]-4-yl)-2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3,4-dihydroxy-3-methyltetrahydrofuran-2-yl)methoxy)-2-(thiazol-4-yl)propanoic acid: ¹H NMR (CD₃OD, 300 MHz) δ 9.04 (s, 1H), 8.21 (s, 1H), 7.27-7.69 (m, 10H), 5.93-5.95 (d, J=7 Hz, 1H), 4.52-4.55 (d, J=8 Hz, 1H), 4.04 (s, 1H), 3.79-3.85 (m, 3H), 1.36 (s, 3H); LC/MS [M+H]=623.2.

Example 200 Synthesis of 4′-(2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3,4-dihydroxy-3-methyltetrahydrofuran-2-yl)methoxy)-2-carboxy-2-(thiazol-4-yl)ethyl)-[1,1′-biphenyl]-2-carboxylic acid

Proceeding as described in Example 179 above but substituting (2R,3R,4R,5R)-5-((6-N,N′-bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyl-2-(hydroxyl-methyl)tetrahydrofuran-3,4-diyl diacetate and BnBr with (2R,3R,4R,5R)-5-(6-(N,N′-bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-2-((2-methoxy-2-oxo-1-(thiazol-4-yl)ethoxy)methyl)-3-methyltetrahydrofuran-3,4-diyl diacetate and 4-(bromomethyl)-1,1′-biphenyl provided the title compound as a mixture of diastereomers (ca. 1:1) and isolated as an off-white solid.

LC/MS [M+H]=667.2.

Example 201 Synthesis of 4′-(2-(((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3,4-dihydroxy-3-methyltetrahydrofuran-2-yl)methoxy)-2-carboxy-2-(1H-tetrazol-5-yl)ethyl)-[1,1′-biphenyl]-2-carboxylic acid

Step 1:

To a solution of ethyl 2-(1H-tetrazol-5-yl)acetate (500 mg, 3.24 mmol) and trimethylsilyl)ethoxymethyl chloride (0.69 mL, 3.89 mmol) in dry DMF (7 mL) under argon atmosphere at 25° C. was added powdered potassium carbonate (896 mg, 6.48 mmol). The reaction mixture was stirred overnight before it was diluted with H₂O (30 mL) and extracted with EtOAc (3×30 mL). The combined organic layer was washed with brine (30 mL) and water (30 mL) and then dried over Na₂SO₄ and concentrated. The residue was purified by CombiFlash silica gel column chromatography (8-58% EtOAc in hexanes) to provide ethyl 2-(2-((2-(trimethylsilyl)ethoxy)methyl)-2H-tetrazol-5-yl)acetate (200 mg) as an oil.

Steps 2-6:

Proceeding as described in Example 1 above but substituting methyl 2-(thiazol-4-yl)acetate with ethyl 2-(2-((2-(trimethylsilyl)ethoxy)methyl)-2H-tetrazol-5-yl)acetate provided a pair of diastereomeric title products (ca. 1:1) which the stereo configuration was assigned arbitrarily. Both products were purified by preparative HPLC and isolated as off-white solids.

¹H NMR (CD₃OD, 300 MHz): Isomer 1: δ 8.50 (s, 1H), 7.73-7.79 (m, 2H), 7.31-7.56 (m, 3H), 7.01-7.24 (m, 4H), 6.04 (d, J=7.87 Hz, 1H), 4.64 (d, J=7.88 Hz, 1H), 4.10-4.14 (m, 1H), 3.46-4.00 (m, 4H), 1.35 (s, 3H); Isomer 2: δ 8.31 (s, 1H), 7.73-7.79 (m, 2H), 7.31-7.56 (m, 3H), 7.01-7.24 (m, 4H), 5.99 (d, J=7.75 Hz, 1H), 4.48 (d, J=7.72 Hz, 1H), 4.19-4.23 (m, 1H), 3.46-4.00 (m, 4H), 1.42 (s, 3H); LC/MS [M+H]=652.2.

Example 202 Synthesis of (((((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)(hydroxy)phosphoryl)methyl)phosphonic acid

Step 1:

To a solution of (2R,3R,4R,5R)-5-(6-(bis-(tert-butoxycarbonyl)amino)-2-chloro-9H-purin-9-yl)-3-ethynyl-2-(hydroxymethyl)tetrahydrofuran-3,4-diyl diacetate (329 mg, 0.539 mmol) in i-PrOH (1.6 mL), MeOH (1.1 mL) and H₂O (0.8 mL) was added powdered LiOH (111 mg, 2.69 mmol). The mixture was stirred for 30 minutes before the organic volatile was removed under reduced pressure and the residue was diluted with H₂O (12 mL). The pH of the aq. layer was adjusted to ˜ 3 with 1N aq. HCl and extracted with EtOAc (3×12 mL). The combined organic layer was dried over MgSO₄, filtered and concentrated to provide tert-butyl (2-chloro-9-((2R,3R,4S,5R)-4-ethynyl-3,4-dihydroxy-5-(hydroxymethyl)tetrahydro-furan-2-yl)-9H-purin-6-yl)carbamate which was used in the next step directly without further purification.

Step 2:

Tert-butyl (2-chloro-9-((2R,3R,4S,5R)-4-ethynyl-3,4-dihydroxy-5-(hydroxymethyl)-tetrahydrofuran-2-yl)-9H-purin-6-yl)carbamate (0.539 mmol) was taken up in a mixture of DCM (1 mL) and TFA (0.5 mL). The reaction mixture was stirred for 3 h before it was concentrated. The residue was taken up in DCM (10 mL) and concentrated again (repeated 5 cycles). The residue was dried further in the vacuum oven for 18 h to provide crude (2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-2-(hydroxymethyl)tetrahydro-furan-3,4-diol as an off-white solid.

Step 3:

To an oven dried flask was charged with crude (2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-2-(hydroxymethyl)tetrahydrofuran-3,4-diol and dry trimethyl phosphate (2.5 mL) under argon atmosphere. The mixture was cooled at 0° C. and followed by dropwise addition of a solution of methylenebis(phosphonic dichloride) (673 mg, 2.7 mmol) in dry trimethyl phosphate (1.1 mL) over 10 minutes. The reaction mixture was stirred at 0° C. for 3 h before a solution of triethylammonium carbonate (1 M, 1.9 mL) was added dropwise. The mixture was stirred for 15 minutes at 0° C. and then stirred for 2 h at ambient temperature. The crude mixture was purified by preparative reversed-phase HPLC to provide a impure product. This impure product was further purified by reserved-phase HPLC twice to provide the desired (((((2R,3S,4R,5R)-5-(6-amino-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)(hydroxy)phosphoryl)methyl)-phosphonic acid (34 mg) as a light brown solid.

¹H NMR (CD₃OD, 300 MHz): δ 8.75 (bs, 1H), 6.07 (br, 1H), 4.86 (bs, 1H), 4.31-4.61 (m, 3H), 3.20 (s, 1H), 2.54 (br, 1H); LC/MS [M+H]=484.0.

Example 203 Synthesis of (((((2R,3S,4R,5R)-5-(6-(benzylamino)-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)(hydroxy)phosphoryl)methyl)phosphonic acid

Step 1:

While under nitrogen, a solution of (3aR,5R,6R,6aR)-5-(((tert-butyldiphenylsilyl)-oxy)methyl)-6-ethynyl-2,2-dimethyltetrahydrofuro[2,3-d][1,3]dioxol-6-ol (14.48 g, 32 mmoL) (prepared using the methods described in Hulpia, F. et al. Bioorg. Med. Chem. Lett. 2016, 26, 1970-1972) in acetic acid (130 mL) was cooled to 14-17° C. and treated with acetic anhydride (32.01 mL, 341 mmoL, 10.7 eq) and concentrated sulfuric acid (576 uL, 10.8 mmoL, 0.34 eq). After stirring at for 2.5 h. The mixture was diluted with ethyl acetate (200 mL each) and washed with water. The aqueous phase was extracted with ethyl acetate (25 mL), and the combined organic solution washed with sodium bicarbonate (aqueous, saturated, 200 mL), dried over Na₂SO₄, filtered, and concentrated. The residual oil was purified by flash column chromatography on silica gel column (0-3% ethyl acetate in dichloromethane) to provide (3R,4R,5R)-5-(((tert-butyldiphenylsilyl)oxy)methyl)-4-ethynyltetrahydrofuran-2,3,4-triyl triacetate as a mixture of anomers and isolated as a white solid in good yield (9.5 g, 55%).

Step 2:

While under nitrogen, 2,6-dichloroadenine (2.91 g, 15.4 mmoL, 1.01 eq) and N,O-bis(trimethylsilyl)acetamide (4.87 mL, 19.6 mmoL, 1.29 eq) in anhydrous acetonitrile (90 mL) was stirred at room temperature. Next, a solution of (2R,3R,4R,5R)-2,4-bis(acetyloxy)-5-{[(tert-butyldiphenylsilyl)oxy]methyl}-4-ethynyloxolan-3-yl acetate (8.2 g, 15.22 mmoL) in anhydrous acetonitrile (10 mL) was added, followed by dropwise addition of trimethylsilyl trifluoromethanesulfonate (3.67 mL, 20.3 mmoL, 1.33 eq). The reaction was warmed to 50° C. for 18 h, then cooled to room temperature. Saturated aqueous sodium bicarbonate (10 mL), was added and the mixture was stirred for ten minutes. The resulting mixture was extracted with ethyl acetate (3×100 mL) and the combined organic layer was dried (Na₂SO₄), filtered, and concentrated. The residue was purified by flash column chromatography on silica gel column (0-30% ethyl acetate in hexanes) to provide (2R,3R,4R,5R)-2-(((tert-butyldiphenylsilyl)oxy)methyl)-5-(2,6-dichloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate as a white solid (8.2 g, 81%).

Step 3:

A solution of (2R,3R,4R,5R)-2-(((tert-butyldiphenylsilyl)oxy)methyl)-5-(2,6-dichloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate (1.6 g, 2.4 mmoL) in anhydrous THF (25 mL) was cooled to 0° C. and treated with acetic acid (0.192 mL, 3.36 mmoL) and tetrabutylammonium fluoride in THF (1N, 3.36 mL, 3.36 mmoL). After the addition was complete, the reaction was warmed to room temperature with continued stirring for 3 h. The reaction mixture was concentrated. The crude residue was purified via flash column chromatography on silica gel (0-50% ethyl acetate in hexanes) to afford (2R,3R,4R,5R)-5-(2,6-dichloro-9H-purin-9-yl)-3-ethynyl-2-(hydroxymethyl)tetrahydrofuran-3,4-diyl diacetate (0.88 g, 86%) as a white foam.

Step 4:

A solution of (2R,3R,4R,5R)-5-(2,6-dichloro-9H-purin-9-yl)-3-ethynyl-2-(hydroxyl-methyl)tetrahydrofuran-3,4-diyl diacetate (100 mg, 0.233 mmoL) in trimethylphosphate (4 mL) was cooled to 0° C. and treated with a second solution of methylenebis(phosphonic dichloride) (116 mg, 0.467 mmoL, 2 eq) in trimethylphosphate (4 mL). After the addition was complete, stirring was continued for 2 h then the cooling bath was removed and stirring was continued for 18 h. Ammonium bicarbonate (0.7 M aqueous TEAB, pH 8.5) was added slowly with vigorous stirring until no more gas evolution was observed. Once quenched, NaHCO₃ (satd., aqueous; 5 mL) was added and mixture stirred for 1 h at room temperature. The reaction mixture was washes with dichloromethane, acidified with 2N HCl to pH-1 and extracted with ethyl acetate (10×50 mL). The combined organic layer was dried over sodium sulfate, filtered and concentrated in vacuo. The residual oil was azeotroped with toluene (3×10 mL) to give (((((2R,3R,4R,5R)-3,4-diacetoxy-5-(2,6-dichloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)(hydroxy)phosphoryl)-methyl)phosphonic acid as an off-white solid that was used in the next step without further purification.

Step 5:

A solution of (((((2R,3R,4R,5R)-3,4-diacetoxy-5-(2,6-dichloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)(hydroxy)phosphoryl)methyl)phosphonic acid from Step 4 (˜90 mg) was dissolved in anhydrous dioxane (8 mL), cooled to 0° C., then treated with diisopropylethylamine (0.085 mL, 0.513 mmoL, 2.2 eq) and benzylamine (0.036 mL, 0.33 mmoL, 1.4 eq). After the addition was complete, the reaction was stirred at room temperature for 18 h and concentrated to provide (((((2R,3R,4R,5R)-3,4-diacetoxy-5-(6-(benzylamino)-2-chloro-9H-purin-9-yl)-3-ethynyltetrahydrofuran-2-yl)methoxy)(hydroxy)-phosphoryl)methyl)phosphonic acid. The crude product was used directly in the subsequent hydrolysis without further purification.

The crude product from Step 5 was dissolved in 1:1 MeOH/THF (2 mL) and treated with LiOH (84 mg, 3.5 mmoL, 15 eq) in water (1 mL). After the addition was complete, the reaction was stirred at room temperature for 18 h before it was acidified to pH-1 with 2N HCl and concentrated. The resulting reaction mixture was diluted in 1:1 acetonitrile in water with 0.1% TFA (4 mL) and purified via reverse phase HPLC to give (((((2R,3S,4R,5R)-5-(6-(benzylamino)-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)(hydroxy)phosphoryl)methyl)phosphonic acid as a white solid (9.2 mg, 7%) after lyophilization.

¹H NMR (D₂O) δ 8.63 (s, 1H), 7.41 (m, 5H), 6.07 (d, J=6.9 Hz, 1H), 4.96 (d, J=7.0 Hz, 1H), 4.46 (s, 1H), 4.37 (d, J=12.0 Hz, 1H), 4.25 (d, J=11.5 Hz, 1H), 3.21 (s, 1H), 2.38 (t, J=20.0 Hz, 2H). HPLC: Rt=17.2 min, 97.9%. ESI-MS for C₂₁H₂₄ClN₅O₉P₂ calcd. 587.07, found 586.8 (M−); ESI-MS for C₁₂H₉ClN₅ calcd. 258.05, found 258.4 (M-ribose fragment).

Example 204 Synthesis of ((((2R,3S,4R,5R)-5-(6-(benzylamino)-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)methyl)phosphonic acid

Step 1:

A flamed dried round bottom flask was charged with diethyl hydroxymethylphos-phonate (780 mg, 4.64 mmol) and triethylamine (0.838 mL, 6.031 mmoL, 1.3 eq) in anhydrous dichloromethane (20 mL) was cooled to −78° C. and treated trifluoromethane-sulfonic anhydride (0.847 mL, 5.10 mmoL, 1.3 eq) dropwise. The reaction was stirred for 10 min as the reaction was warmed to 0° C. After 30 min, the reaction mixture was poured into ether (precooled to 0° C.) and the crystalline precipitate filtered. The filtrate was then washed sequentially with water (1×100 mL), 1 M HCl (1×100 mL), and saturated aqueous sodium chloride (1×125 mL). Organic layer was dried (MgSO₄), filtered, and concentrated to provide crude (diethoxyphosphoryl)methyl trifluoromethanesulfonate obtained as a yellow oil, was dissolved in anhydrous THF and this solution used directly in the next step without further purification.

Step 2:

A solution of (2R,3R,4R,5R)-5-(2,6-dichloro-9H-purin-9-yl)-3-ethynyl-2-(hydroxyl-methyl)tetrahydrofuran-3,4-diyl diacetate (350 mg, 0.815 mmoL) and (diethoxyphosphoryl)-methyl trifluoromethanesulfonate (294 mg, 0.978 mmoL, 1.2 eq) in THF (20 mL) was cooled to −78° C. and treated with LiHMDS (1M in THF; 0.980 mL, 0.978 mmoL, 1.2 eq) in a dropwise. After stirring for 1.5 h, reaction was quenched with solid NH₄Cl, diluted with water and extracted with ethyl acetate. The organic layer was dried (MgSO₄), filtered, and concentrated. Purification by flash column chromatography on silica gel (0-100% ethyl acetate in hexanes) afforded (2R,3R,4R,5R)-5-(2,6-dichloro-9H-purin-9-yl)-2-(((diethoxy-phosphoryl)methoxy)methyl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate (140 mg, 30%) as a pale yellow oil.

Step 3:

A solution of (2R,3R,4R,5R)-5-(2,6-dichloro-9H-purin-9-yl)-2-(((diethoxyphos-phoryl)methoxy)methyl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate (85 mg, 0.147 mmoL) and diisopropylethylamine (40 μL, 0.235 mmoL, 1.6 eq) in anhydrous dioxane (8 mL) was cooled to 0° C. was treated with benzylamine (19 μL, 0.176 mmoL, 1.2 eq). After the addition was complete, the reaction was warmed to room temperature and stirred for 18 h. The mixture was diluted with water and extracted with ethyl acetate. The organic layer was dried (Na₂SO₄), filtered, and concentrated to provide crude (2R,3R,4R,5R)-5-(6-(benzylamino)-2-chloro-9H-purin-9-yl)-2-(((diethoxyphosphoryl)methoxy)methyl)-3-ethynyltetrahydrofuran-3,4-diyl diacetate (93 mg, 96%) as a white solid which was used directly in the subsequent step without further purification.

Step 4:

The crude product from the previous step was dissolved in anhydrous acetonitrile (10 mL) and treated with bromotrimethylsilane (0.24 mL, 1.8 mmoL, 12 eq) dropwise. After the addition was complete, the solution was stirred at room temperature for 22 h and quenched with water (5 mL). After stirring an additional 2-3 min, the solution was extracted with ethyl acetate (4×100 mL). The organic layer was, dried (Na₂SO₄), filtered, and concentrated to afford ((((2R,3S,4R,5R)-5-(6-(benzylamino)-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetra-hydrofuran-2-yl)methoxy)methyl)phosphonic acid as an off-white solid. This crude solid was dissolved in absolute EtOH at 0° C. and treated with KOEt (51 mg, 0.61 mmoL, 4 eq) in one portion. The reaction was stirred at room temperature for 20 min before it was acidified with AcOH (0.52 mL, 0.91 mmoL, 6 eq) and stirred an additional 10 min. The crude product was purified via reverse-phase HPLC and dried by lyophilization to give ((((2R,3S,4R,5R)-5-(6-(benzylamino)-2-chloro-9H-purin-9-yl)-3-ethynyl-3,4-dihydroxytetrahydrofuran-2-yl)methoxy)methyl)phosphonic acid (6 mg, 7%) as a white solid.

¹H NMR (D₂O) δ 8.41 (s, 1H), 7.19 (m, 5H), 5.84 (d, J=7.2 Hz, 1H), 4.82 (d, J=7.1 Hz, 1H), 4.21 (m, 1H), 4.19 (m, 2H), 3.79 (d, J=3.8 Hz, 2H), 3.57 (m, 2H), 2.98 (s, 1H).

HPLC: Rt=7.19 min, 97.5%. ESI-MS for C₂₀H₂₁ClN₅O₇P calcd, 509.09, found 509 (M+); ESI-MS for C₁₁H₈ClN₆ calcd. 258.05, found 259 (M-ribose fragment).

Example 205 Synthesis of (((((2R,3S,4R,5R)-5-(6-(benzylamino)-2-chloro-9H-purin-9-yl)-3,4-dihydroxy-3-methyltetrahydrofuran-2-yl)methoxy)(hydroxy)phosphoryl)methyl)phosphonic acid

Step 1:

While under nitrogen an ice-cooled solution of (3aR,5R,6aS)-5-(((tert-butyldiphenyl-silyl)oxy)methyl)-2,2-dimethyldihydrofuro[2,3-d][1,3]dioxol-6 (5H)-one (6 g, 14.1 mmoL) in anhydrous THF (100 mL) was treated with 3M methyl magnesium chloride in THF (5.9 mL, 1.4 eq) dropwise. After the addition was complete, the cooling bath was removed, and stirring was continuing for 1 h. The mixture was cooled back to 0° C. and quenched with a saturated aqueous ammonium chloride (10 mL), diluted with ethyl acetate (100 mL) and washed with water (80 mL). The aqueous was re-extracted with ethyl acetate (1×50 mL) and the combined organic layer was dried over sodium sulfate, filtered, and concentrated. The residual oil was purified by flash column chromatography on silica (0-30% ethyl acetate in hexanes) to provide (3aR,5R,6R,6aR)-5-(((tert-butyldiphenylsilyl)oxy)methyl)-2,2,6-trimethyltetrahydrofuro[2,3-d][1,3]dioxol-6-ol as a pale viscous oil (4.2 g, 67%).

Step 2:

While under nitrogen, a solution of (3aR,5R,6aS)-5-(((tert-butyldiphenylsilyl)oxy)-methyl)-2,2-dimethyldihydrofuro[2,3-d][1,3]dioxol-6 (5H)-one (2.25 g, 5.08 mmoL) in dichloromethane (35 mL) and water (3.5 mL) cooled to 0° C. and treated with trifluoroacetic acid (15 mL). After 2.5 h, saturated aqueous NaHCO₃ was added until the solution was pH-8 and mixture was extracted with dichloromethane (2×150 mL). The combined organic layer was dried over sodium sulfate, filtered, and concentrated. The crude oil was azeotroped with toluene (3×5 mL), diluted with dichloromethane (45 mL) was treated with pyridine (12 mL), acetic anhydride (4.77 mL, 50.83 mmoL) and catalytic 4-DMAP (142 mg, 1.17 mmoL). After stirring 18 h, the reaction was diluted with ethyl acetate (200 mL each) and washed sequentially with saturated aqueous NH₄Cl (3×100 mL), 0.5 N HCl (2×100 mL), and saturated aqueous sodium chloride (1×120 mL). The combined organic layer was dried over sodium sulfate, filtered, and concentrated. The residual oil was purified by flash column chromatography on silica gel (0-30% ethyl acetate in hexanes) to provide (3R,4R,5R)-5-(((tert-butyldiphenylsilyl)oxy)methyl)-4-methyltetrahydrofuran-2,3,4-triyl triacetate (2.1 g, 78%) as colorless solid.

Steps 3-6:

Proceeding as described in Example 203 above but substituting (3aR,5R,6R,6aR)-5-(((tert-butyldiphenylsilyl)-oxy)methyl)-6-ethynyl-2,2-dimethyltetrahydrofuro[2,3-d][1,3]-dioxol-6-ol with (3aR,5R,6aS)-5-(((tert-butyldiphenyl-silyl)oxy)methyl)-2,2-dimethyldihydrofuro[2,3-d][1,3]dioxol-6 (5H)-one provided the title compound (8 mg, 3%) as as a white solid.

¹H NMR (D₂O:DMSO-d₆, 6:1) 8.46 (bs, 1H), 7.23 (m, 5H), 5.84 (d, J=6.9 Hz, 1H), 4.45 (d, J=7.0 Hz, 1H), 4.12 (s, 1H), 3.95 (m, 3H), 3.54 (m, 1H), 2.18 (bs, 2H), 1.31 (s, 3H). ESI-MS for C₁₉H₂₄ClN₅O₉P₂ calcd. 563.1, found 562.1 (M−).

Example 206 Assay 1: Inhibition of the CD73 Enzyme In Vitro

For measurements of soluble CD73 enzyme activity, recombinant CD73 was obtained from R&D Systems, Cat. No. 5795-EN-010. Serial dilutions of test compounds were incubated with recombinant CD73 and AMP in reaction buffer (25 mM Tris HCl pH7.5, 5 mM MgCl₂, 50 mM NaCl, 0.25 mM DTT, 0.005% Triton X-100). The final reaction volume was 25 μL and the final concentrations of recombinant CD73 and AMP were 0.5 nM and 50 μM, respectively. Reactions were allowed to proceed for 30 minutes at room temperature before the addition of 100 μL Malachite Green (Cell Signaling Technology, Cat. No. 12776). After 5 minutes at room temperature, absorbance at 630 nm was determined on a microplate spectrophotometer. The concentration of inorganic phosphate was determined using a phosphate standard curve.

Assay 2: Inhibition of the CD73 Enzyme In Vitro

For measurements of soluble CD73 enzyme activity, recombinant CD73 was obtained from R&D Systems, Cat. No. 5795-EN-010. Serial dilutions of test compounds were incubated with recombinant CD73 and AMP in reaction buffer (25 mM Tris HCl pH7.5, 5 mM MgCl₂, 50 mM NaCl, 0.25 mM DTT, 0.005% Triton X-100). The final reaction volume was 25 μL and the final concentrations of recombinant CD73 and AMP were 0.05 nM and 50 μM, respectively. Reactions were allowed to proceed for 1 hour at 37° C. before the addition of 100 μL Malachite Green (Cell Signaling Technology, Cat. No. 12776). After 5 minutes at room temperature, absorbance at 630 nm was determined on a microplate spectrophotometer. The concentration of inorganic phosphate was determined using a phosphate standard curve.

The IC₅₀ data for both assays is given below in Table 2. ND indicates not determined.

TABLE 2 Assay 1 Assay 2 CD73 CD73 Example IC50 IC50 # Compound (nM) (nM)  1

ND 1.7  2

ND 147  3

ND 1  4

ND 0.5  5

ND 4  6

52 ND  7

ND 2  8

ND 2  9

ND 0.17  10

ND 0.26  11

ND 0.06  12

ND 0.1  13

ND 0.3  14

ND 0.6  15

ND 20  16

ND 24  17

ND 347  18

ND 0.3  19

ND 0.2  20

ND 0.2  21

ND 0.3  22

ND 0.3  23

5 ND  24

1.8 ND  25

7 ND  26

58 ND  27

18 ND  28

3 ND  29

2 ND  30

ND 5  31

ND 2  32

ND 3  33

ND 2  34

ND 2  35

ND 4  36

ND 4  37

ND 6  38

ND 3  39

ND 3  40

ND 3  41

ND 0.6  42

ND 1  43

ND 2  44

ND 62  45

ND 1  46

ND 1  47

ND 2  48

ND 0.5  49

273 ND  50

3 ND  51

3 ND  52

4 ND  53

ND 0.3  54

ND 0.2  55

35 ND  56

ND >200  57

ND 103  58

ND 1.6  59

1 ND  60

3 ND  61

1.5 ND  62

ND 2  63

ND 1  64

ND 3  65

ND 1  66

ND 0.3  67

ND 0.8  68

ND 0.8  69

ND 3  70

ND 1  71

ND 6  72

ND 3  73

ND 1  74

ND 2  75

ND 0.6  76

ND 6  77

ND 2  78

ND 2  79

ND 4  80

ND 2  81

ND 0.4  82

ND 2  83

ND 1  84

ND 3  85

ND 2  86

ND 1  87

ND 0.6  88

ND 1.2  89

ND 1.1  90

0.9 ND  91

0.3 ND  92

0.8 ND  93

1.7 ND  94

ND 5  95

ND 7  96

ND 3  97

ND 2  98

ND 2  99

ND 6 100

ND 2 101

ND 1 102

ND 1 103

ND 3 104

ND 2 105

ND 2 106

ND 296 107

ND 506 108

ND 3 109

ND 284 110

ND 3 111

ND 2,666 112

ND 1,357 113

331 ND 114

177 ND 115

135 ND 116

8,049 ND 117

ND 58 118

ND 48 119

ND 4,612 120

4,628 ND 121

ND 1,711 122

ND 40 123

71 ND 124

27 ND 125

ND 235 126

ND 9 127

ND 170 128

ND 6 129

1,580 ND 130

ND 0.36 131

ND >100 132

ND ND 133

ND 7 134

ND 16 135

ND 91 136

ND 0.24 137

ND 0.31 138

ND 0.15 139

ND 0.13 140

ND 0.29 141

ND 0.23 142

ND 5 143

ND 13 144

ND 1 145

ND 108 146

ND 0.41 147

ND 0.58 148

ND 0.08 149

ND 0.11 150

ND 0.16 151

ND 0.25 152

ND 0.05 153

ND 0.48 154

ND 2 155

ND 2 156

ND 0.14 157

ND 0.37 158

ND 8 159

ND 476 160

ND 0.31 161

ND 561 162

ND 0.42 163

ND >100 164

ND 261 165

ND 45 166

ND 145 167

ND 139 168

ND 14 169

ND 162 170

ND 8 171

ND 96 172

ND 6 173

ND 112 174

ND 17 175

ND 1 176

ND 5 177

ND ND 178

ND ND 179

320 ND 180

9 ND 181

21 ND 182

24 ND 183

56 ND 184

102 ND 185

11748 ND 186

8833 ND 187

10 ND 188

134 ND 189

1851 ND 190

9316 ND 191

7 ND 192

25 ND 193

263 ND 194

336 ND 195

236 ND 196

82 ND 197

ND 0.73 198

2268 ND 199

5757 ND 200

6091 ND 201

204 ND 202

148 ND 203

4.2 ND 204

100 ND 205

12 ND

Example 207 Activation of Tumor-Directed Immune Response with CD73 Inhibitors

EG7 cells were implanted subcutaneously into C57BL/6 mice. Compound 9 (50 mg/kg) or vehicle was orally administered BID starting day one post implant (N=10 per group). Tumors were excised on day 14 and analyzed by flow cytometry. Compound 9 increased the % CD8+ cells of CD45+ cells as shown in FIG. 1A (* indicates p<0.05). EG7 cells were implanted subcutaneously into C57BL/6 mice. Anti-CD8 antibody was dosed i.p. on days −1, 0, 5, and 10. Compound 9 (50 mg/kg) or vehicle was orally dosed BID starting on day 1. FIG. 1B shows that depletion of CD8+ T cells reverses efficacy (**** indicates p<0.0001 vs Compound 9+anti-CD8). Compound 9 alone showed more of a tumor volume reduction that the combination of Compound 9 than the anti-CD8 antibody.

Example 208 Reversal of AMP-Mediated Suppression of CD8+ T Cells Using CD73 Inhibitors

Human CD8+ T cells were labeled with CellTrace CFSE and then pre-incubated with an adenosine deaminase inhibitor and Compound 9 or vehicle for 20 minutes. 20 μM AMP was added for assessing T cell proliferation and CD25 expression. 10 μM AMP was added for assessing cytokine production. T cells were activated with α-CD3, α-CD28, and hIL2. After 4 days, proliferation and CD25 expression were assessed by flow cytometry and cytokine levels in the supernatant were measured by ELISA. EC₅₀s were determined using a four-parameter dose-response curve equation. FIG. 2A depicts the EC₅₀=11.6 nM for CD8+ T cell proliferation. FIG. 2B depicts the EC₅₀=9.6 nM for CD8+ T cell activation. FIG. 2C depicts the EC₅₀=4.5 nM for IFNy production. FIG. 2D depicts the EC₅₀=5.6 nM for Granzyme B production.

Example 209 Selectivity of CD73 Inhibitors

Compounds of the invention are selective for CD73 and do not exhibit proliferative effects. Using Compound 9, the activity of cell surface CD39 was assessed using K562 cells expressing human CD39 and Kinase-Glo. Activity of recombinant human ENTPD2 and ENTPD3 was assessed using a malachite green assay. Each of the enzymes CD39, ENTPD2 AND ENTPD3 all showed an IC₅₀ of >10,000 nM. Compound 9 was screened in the Eurofins Safety Screen Panel and the Eurofins Express Diversity Kinase Profile Panel. In the Safety Panel, 1/87 targets were inhibited at >50% at 10 μM of Compound 9. The PDE3 enzyme was inhibited at 59%. In the Kinase Panel, none of the 45 targets were inhibited at >50%.

Further, Compound 9 did not show anti-proliferative effects against three cell lines. Viability of EG7 and A375 cells treated with 100 μM Compound 9 was measured using CellTiter-Glo after 3 days. Proliferation of human CD8+ T cells was measured by flow cytometry after 4 days of treatment with 100 μM Compound 9 using CellTrace CFSE Cell Proliferation Kit. FIG. 3A shows the comparable % cell survival of EG7 cells, a mouse T cell lymphoma cell line. FIG. 3B shows the comparable % cell survival of A375 cells, a human melanoma cell line. FIG. 3C shows the comparable % divided cells of human CD8+ T cells.

Example 210 CD73 Inhibition

The potency of Compound 9 was evaluated against recombinant CD73 and CD73-expressing SK-MEL-28 cells using a malachite green assay. Inhibition of CD73 in plasma was measured using LC/MS to assess conversion of ¹⁵N₅-AMP into ¹⁵N₅-ADO. FIG. 4A indicates the nanomolar inhibition of CD73 cells from both human and mouse sources. FIG. 4B depicts the IC₅₀=0.17 nM for human recombinant CD73 cells. FIG. 4C depicts the IC₅₀=0.38 nM for human plasma CD73 cells. Inhibition of CD73 in plasma was measured using LC/MS to assess conversion of ¹⁵N₅-AMP into ¹⁵N₅-ADO. FIG. 4D depicts the IC₅₀=0.21 nM for human CD73 cell surface.

Example 211 CD73 Inhibitor Oral Dosing Phamacodynamics

Single dose Compound 9 (50 mg/kg) was administered orally to mice and plasma was collected at indicated time points. Compound 9 levels were measured by LC/MS. The IC₅₀ in mouse plasma was 1 nM as shown in FIG. 5A. Plasma was harvested from mice 2 hours post dose and spiked with ¹⁵N₅-AMP and a TNAP inhibitor. ¹⁵N₅-ADO levels were measured by LC/MS. FIG. 5B depicts the 92% inhibition of mouse plasma CD73 cells.

Example 212 Single-Agent Efficacy of Orally Dosed CD73 Inhibitors

Compounds of the invention show potent anti-tumor effects, evidenced in reducing tumor volume in a mouse model. In one model, EG7 cells were implanted subcutaneously into C57BL/6 mice. Compound 9 or vehicle was orally administered BID starting day one post implant (N=10 per group). FIG. 6A depicts the further decrease in tumor volume with increasing doses of Compound 9. In another model, EG7 cells were implanted subcutaneously into C57BL/6 mice. Compound 9 was orally administered BID (100 mg/kg) starting day one post implant (N=10 per group). Vehicle was orally administered BID starting day one post implant (N=20) until day five post implant, at which time, mice were randomized by tumor volume into two groups. Compound 9 (100 mg/kg) or vehicle was orally administered BID to N=10 per group starting day six post implant. FIG. 13A depicts the decrease in tumor volume with administration of Compound 9 to mice harboring established tumors. FIGS. 13B-D show individual replications of this measurement for each dosing. FIG. 13B is vehicle. FIG. 13C is dosing of Compound 9 started on day 1. FIG. 13D is Compound 9 started on day 6. In another model, CT26 cells were implanted subcutaneously into Balb/c mice. 100 mg/kg Compound 9 or vehicle was orally administered BID starting day one post implant (N=10 per group). FIG. 6B depicts the decrease in tumor volume compared to vehicle. **** indicates p<0.0001 vs vehicle; NS indicates not significant (two-way ANOVA).

Example 213 CD73 Inhibitor Efficacy in Combination with Immunooncology and Chemotherapeutic Agents

EG7 cells were implanted subcutaneously into C57BL/6 mice for each experiment. Anti-PD-L1 antibody (5 mg/kg) was dosed i.p. on Study Days 3, 5, 7, 9, 11, 13. Compound 9 (100 mg/kg) or vehicle was orally administered BID starting one day post implant. FIG. 7A depicts the reduction in tumor volume with single agent and combination therapy. ** indicates p<0.01; **** indicates p<0.0001 (two-way ANOVA). FIGS. 7B-7E show the individual replications of this measurement for each dosing. FIG. 7B is vehicle, FIG. 7C is anti-PD-L1 antibody, FIG. 7D is Compound 9, and FIG. 7E is Compound 9+Anti-PD-L1.

Oxaliplatin was dosed i.p. 6 mg/kg on Study Days 7 and 14. Compound 9 (100 mg/kg) or vehicle was orally administered BID starting one day post implant. FIG. 8A depicts the reduction in tumor volume with single agent and combination therapy. **** indicates p<0.0001 (two-way ANOVA). FIGS. 8B-8E show the individual replications of this measurement for each dosing. FIG. 8B is vehicle, FIG. 8C is oxaliplatin, FIG. 8D is Compound 9, and FIG. 8E is Compound 9+oxaliplatin.

Doxorubicin was dosed i.v. 2.5 mg/kg on Study Days 7 and 14. Compound 9 (50 mg/kg) or vehicle was orally administered BID starting one day post implant. FIG. 9A depicts the reduction in tumor volume with single agent and combination therapy. * indicates p<0.05; *** indicates p<0.001 (two-way ANOVA). FIGS. 9B-9E show the individual replications of this measurement for each dosing. FIG. 9B is vehicle, FIG. 9C is doxorubicin, FIG. 9D is Compound 9, and FIG. 9E is Compound 9+doxorubicin.

Docetaxel was dosed i.p. 5 mg/kg on Study Days 5, 12, and 19. Compound 9 (100 mg/kg) or vehicle was orally administered BID starting one day post implant. FIG. 12A depicts the reduction in tumor volume with single agent and combination therapy. * indicates p<0.05; **** indicates p<0.0001 (two-way ANOVA). FIGS. 12B-10E show the individual replications of this measurement for each dosing. FIG. 12B is vehicle, FIG. 12C is docetaxel, FIG. 12D is Compound 9, and FIG. 12E is Compound 9+docetaxel.

Example 214 CD73 Inhibitor Efficacy in Multiple Tumors

Serum was procured from Discovery Life Sciences. Serum from head and neck squamous cell carcinoma (HNSCC), ovarian cancer, triple-negative breast cancer and esophageal cancer patients were incubated with a serial dilution of Compound 9 in the presence of a TNAP inhibitor. Conversion of ¹⁵N₅-AMP to ¹⁵N₅-ADO was measured by LC/MS. FIG. 10A depicts the sub-nanomolar inhibition of HNSCC serum. FIG. 10B depicts the sub-nanomolar inhibition of ovarian cancer serum. FIG. 10C depicts the sub-nanomolar inhibition of TNBC serum. FIG. 10D depicts the sub-nanomolar inhibition of esophageal cancer serum.

Example 215 Expression of CD73 in Multiple Human Tumors

FIG. 11 depicts normalized mRNA expression levels of CD73 in tumor and normal tissues. Expression levels of CD73 (NT5E) were obtained from the TCGA (tumor) or GTEX (normal) databases using the UCSC Xena platform and analyzed using an unpaired t-test. The expression of CD73 as measured by a Log₂ (Normalized Count+1) was greater than vehicle for pancreatic, esophageal, stomach, head and neck, colon, lung and kidney clear cell tumors.

INCORPORATION BY REFERENCE

All publications and patents mentioned herein are hereby incorporated by reference in their entirety as if each individual publication or patent was specifically and individually indicated to be incorporated by reference. In case of conflict, the present application, including any definitions herein, will control.

EQUIVALENTS

While specific embodiments of the subject invention have been discussed, the above specification is illustrative and not restrictive. Many variations of the invention will become apparent to those skilled in the art upon review of this specification and the claims below. The full scope of the invention should be determined by reference to the claims, along with their full scope of equivalents, and the specification, along with such variations. 

The invention claimed is:
 1. A method of treating a disease or disorder selected from cancer, cerebral and cardiac ischemic diseases, fibrosis, immune and inflammatory disorders, inflammatory gut motility disorder, neurological, neurodegenerative and CNS disorders and diseases, depression, Parkinson's disease, and sleep disorders, the method comprising administering to a subject a therapeutically effective amount of a CD73 inhibitor, wherein the CD73 inhibitor comprises a compound having the following formula:

or a pharmaceutically acceptable salt and/or prodrug thereof, wherein Y is

Het is an optionally substituted purinyl ring or an optionally substituted 5-methyl-pyrimidin-2,4-dione ring; R^(1a) is selected from H, halo, hydroxy, cyano, azido, amino, C₁₋₆alkyl, hydroxyC₁₋₆alkyl, amino-C₁₋₆alkyl, —O—C(O)—O—C₁₋₆alkyl, C₁₋₆acyloxy, C₁₋₆alkoxy, C₂₋₆alkenyl, and C₂₋₆alkynyl; R^(1b) is selected from H, halo, C₁₋₆alkyl, hydroxy-C₁₋₆alkyl, amino-C₁₋₆alkyl, C₂₋₆alkenyl, and C₂₋₆alkynyl; R^(2a) is selected from halo, hydroxy, cyano, azido, amino, C₁₋₆alkyl, hydroxy-C₁₋₆alkyl, amino-C₁₋₆alkyl, C₁₋₆acyloxy, —O—C(O)—O—C₁₋₆alkyl, C₁₋₆alkoxy, C₂₋₆alkenyl, and C₂₋₆alkynyl; R^(2b) is C₂₋₆alkynyl; R³ is selected from H and alkyl; R⁴ is selected from H, alkyl, CN, aryl, heteroaryl, —C(O)OR⁹, —C(O)NR¹¹R¹², —S(O)₂R¹⁰, —P(O)(OR¹¹)(OR¹²), and —P(O)(OR¹¹)(NR¹³R¹⁴); R⁵ is aralkyl or heteroaralkyl, wherein the aralkyl or heteroaralkyl is optionally substituted with one or more substituents selected from halo, haloalkyl, alkyl, alkoxy, carbonyl, aryl, amino, amido, cycloalkyl, heterocyclyl, and heteroaryl; R⁶ is selected from —C(O)OR⁹, —C(O)NR¹⁶R¹⁷, and —P(O)(OR¹¹)(OR¹²); R⁹ is independently selected from H, alkyl, cycloalkyl, cycloalkylalkyl, heterocyclyl, heterocyclylalkyl, aryl, aralkyl, heteroaryl, and heteroaralkyl; R¹⁰ is independently selected from alkyl, alkenyl, alkynyl, amino, cycloalkyl, cycloalkylalkyl, heterocyclyl, heterocyclylalkyl, aryl, aralkyl, heteroaryl, and heteroaralkyl; and each R¹¹ and R¹² is independently selected from H, alkyl, cycloalkyl, cycloalkylalkyl, heterocyclyl, heterocyclylalkyl, aryl, aralkyl, heteroaryl, and heteroaralkyl; or R¹¹ and R¹², together with the nitrogen atom to which they are attached, form a 5- to 7-membered heterocyclyl; R¹³ is, independently for each occurrence, H or alkyl; R¹⁴ is, independently for each occurrence, alkyl or aralkyl; each R¹⁵ is independently selected from hydroxy, alkoxy acyloxy and NR¹³R¹⁴; each R¹⁶ and R¹⁷ is independently selected from H, hydroxy, alkyl, cycloalkyl, cycloalkylalkyl, heterocyclyl, heterocyclylalkyl, aryl, aralkyl, heteroaryl, heteroaralkyl; or R¹⁶ and R¹⁷, together with the nitrogen atom to which they are attached, form a 5- to 7-membered heterocyclyl.
 2. The method of claim 1, wherein the disease or disorder is cancer and the cancer is selected from bladder cancer, bone cancer, brain cancer, breast cancer, cardiac cancer, cervical cancer, colon cancer, colorectal cancer, esophageal cancer, fibrosarcoma, gastric cancer, gastrointestinal cancer, head & neck cancer, Kaposi's sarcoma, kidney cancer, leukemia, liver cancer, lung cancer, lymphoma, melanoma, myeloma, ovarian cancer, pancreatic cancer, penile cancer, prostate cancer, testicular germcell cancer, thymoma and thymic carcinoma.
 3. The method of claim 2, wherein the cancer is selected from breast cancer, brain cancer, colon cancer, fibrosarcoma, kidney cancer, lung cancer, melanoma, ovarian cancer, and prostate cancer.
 4. The method of claim 2, wherein the cancer is breast cancer.
 5. The method of claim 2, further comprising conjointly administering one or more additional chemotherapeutic agents.
 6. The method of claim 5, wherein the one or more additional chemotherapeutic agents are selected from 1-amino-4-phenylamino-9,10-dioxo-9,10-dihydroanthracene-2-sulfonate (acid blue 25), 1-amino-4-[4-hydroxyphenyl-amino]-9,10-dioxo-9,10-dihydroanthracene-2-sulfonate, 1-amino-4-[4-aminophenylamino]-9,10-dioxo-9,10-dihydroanthracene-2-sulfonate, 1-amino-4-[1-naphthylamino]-9,10-dioxo-9,10-dihydroanthracene-2-sulfonate, 1-amino-4-[4-fluoro-2-carboxyphenylamino]-9,10-dioxo-9,10-dihydroanthracene-2-sulfonate, 1-amino-4-[2-anthracenylamino]-9,10-dioxo-9,10-dihydroanthracene-2-sulfonate, navitoclax (ABT-2631, afatinib dimaleate, axitinib, aminoglutethimide, amsacrine, anastrozole, adenosine 5′-(α,β-methylene)diphosphate (APCP), asparaginase, capivasertib (AZD5363), Bacillus Calmette-Guerin vaccine (bcg), bicalutamide, bleomycin, bortezomib, β-methylene-ADP (AOPCP), buserelin, busulfan, cabazitaxel, cabozantinib, campothecin, capecitabine, carboplatin, carfilzomib, carmustine, ceritinib, chlorambucil, chloroquine, cisplatin, cladribine, clodronate, cobimetinib, colchicine, crizotinib, cyclophosphamide, cyproterone, cytarabine, dacarbazine, dactinomycin, daunorubicin, demethoxyviridin, dexamethasone, dichloroacetate, dienestrol, diethylstilbestrol, docetaxel, doxorubicin, epirubicin, eribulin, erlotinib, estradiol, estramustine, etoposide, everolimus, exemestane, filgrastim, fludarabine, fludrocortisone, fluorouracil, fluoxymesterone, flutamide, gefitinib, gemcitabine, genistein, goserelin, trametinib (GSK1120212), hydroxyurea, idarubicin, ifosfamide, imatinib, interferon, irinotecan, ixabepilone, lenalidomide, letrozole, leucovorin, leuprolide, levamisole, lomustine, lonidamine, mechlorethamine, medroxyprogesterone, megestrol, melphalan, mercaptopurine, mesna, metformin, methotrexate, miltefosine, mitomycin, mitotane, mitoxantrone, 8-[4-(1-aminocyclobutyl)phenyl]-9-phenyl[1,2,4]triazolo[3,4-f][1,6]naphthyridin-3 (2H)-one (MK-2206), mutamycin, N-(4-sulfamoylphenylcarbamothioyl) pivalamide, 8,8′-(carbonylbis(imino-4,1-phenylenecarbonylimino-4,1-phenylenecarbonylimino)) bis(1,3,5-naphthalenetrisulfonic acid) (NF279), 4,4′,4″4″′-(carbonylbis(imino-5,1,3-benzenetriylbis(carbonylimino)))tetrakis-benzene-1,3-disulfonic acid (NF449), nilutamide, nocodazole, octreotide, olaparib, oxaliplatin, paclitaxel, pamidronate, pazopanib, pemexetred, pentostatin, perifosine, 2-amino-8-[trans-4-(2-hydroxyethoxy)cyclohexyl]-6-(6-methoxy-3-pyridinyl)-4-methyl-pyrido[2,3-d]pyrimidin-7 (8H)-one (PF-04691502), plicamycin, pomalidomide, porfimer, pyridoxalphosphate-6-azophenyl-2′,4′-disulfonic acid (PPADS), procarbazine, quercetin, raltitrexed, ramucirumab, reactive blue 2, rituximab, rolofylline, romidepsin, rucaparib, selumetinib, sirolimus, sodium 2,4-dinitrobenzenesulfonate, sorafenib, streptozocin, sunitinib, suramin, talazoparib, tamoxifen, temozolomide, temsirolimus, teniposide, testosterone, thalidomide, thioguanine, thiotepa, titanocene dichloride, tonapofylline, topotecan, trametinib, trastuzumab, tretinoin, veliparib, vinblastine, vincristine, vindesine, vinorelbine, and vorinostat (SAHA).
 7. The method of claim 5, wherein the one or more additional chemotherapeutic agents are selected from 1-amino-4-phenylamino-9,10-dioxo-9,10-dihydroanthracene-2-sulfonate (acid blue 25), 1-amino-4-[4-hydroxyphenyl-amino]-9,10-dioxo-9,10-dihydroanthracene-2-sulfonate, 1-amino-4-[4-aminophenylamino]-9,10-dioxo-9,10-dihydroanthracene-2-sulfonate, 1-amino-4-[1-naphthylamino]-9,10-dioxo-9,10-dihydroanthracene-2-sulfonate, 1-amino-4-[4-fluoro-2-carboxyphenylamino]-9,10-dioxo-9,10-dihydroanthracene-2-sulfonate, 1-amino-4-[2-anthracenylamino]-9,10-dioxo-9,10-dihydroanthracene-2-sulfonate, APCP, β-methylene-ADP (AOPCP), capecitabine, cladribine, cytarabine, fludarabine, doxorubicin, gemcitabine, N-(4-sulfamoylphenylcarbamothioyl) pivalamide, NF279, NF449, PPADS, quercetin, reactive blue 2, rolofylline sodium 2,4-dinitrobenzenesulfonate, sumarin, and tonapofylline.
 8. The method of claim 5, wherein the additional chemotherapeutic agent is an immuno-oncology agent.
 9. The method of claim 1, wherein provisos a) or b) apply, wherein provisos a) and b) are as follows: a) if R⁴ and R⁶ are each —C(O)OH and R⁵ is benzyl substituted on the phenyl ring with a heterocyclyl or heteroaryl substituent, then the heterocyclyl or heteroaryl substituent is selected from unsubstituted or substituted pyrrolidinyl, piperazinonyl, piperidonyl, tetrahydropyrimidonyl, pyridonyl, and pyridyl; and b) if R⁴ is —C(O)OH or tetrazolyl, R⁵ is —C(O)OH, and R⁵ is benzyl substituted on the phenyl ring with a second phenyl ring, then either the benzyl phenyl ring or the second phenyl ring is substituted with —C(O)OR⁹ where R⁹ is H or alkyl.
 10. The method of claim 1, wherein R⁵ is aralkyl or heteroaralkyl with a para substituent on the aryl or heteroaryl ring selected from heterocyclyl, heteroaryl, and aryl; and R^(2b) is substituted or unsubstituted C₂alkynyl.
 11. The method of claim 1, wherein Y is


12. The method of claim 1, wherein R⁵ is benzyl substituted on the phenyl ring with a heterocyclyl or heteroaryl substituent, wherein: the phenyl ring substituent is selected from substituted piperidonyl, piperazinonyl, tetrahydropyrimidonyl, pyridonyl, and pyridyl, and, optionally, the piperidonyl, tetrahydropyrimidonyl, pyridonyl, or pyridyl is substituted with one or more of alkyl, hydroxyalkyl or alkoxyalkyl.
 13. The method of claim 1, wherein R⁵ is benzyl substituted on the phenyl ring with


14. The method of claim 1, wherein

represents


15. The method of claim 1, wherein Y is


16. The method of claim 15, wherein each R¹⁵ is hydroxy.
 17. The method of claim 1, wherein Het is selected from


18. The method of claim 1, wherein Het is

wherein Z is CH or N; R^(a) is selected from H, halo, hydroxy, alkyl, thiophenyl, —NR⁷R⁸, aralkyl, aryl, and heteroaryl; R^(b) is selected from halo, alkyl, haloalkyl, hydroxyalkyl, alkylthio, amido, carbonyl, amido, and heteroaryl; R⁷ is selected from H, hydroxy, alkyl, aralkyl, heteroaralkyl, cycloalkyl, and heterocyclyl; and R⁸ is H or alkyl; or R⁷ and R⁸, together with the nitrogen atom to which they are attached, form a 4- to 7-membered heterocyclyl ring.
 19. The method of claim 18, wherein Het is


20. The method of claim 18, wherein R^(a) is selected from H, halo, alkyl, thienyl, —NR⁷R⁸, aryl, and heteroaryl.
 21. The method of claim 18, wherein R^(b) is selected from halo, alkyl, hydroxyalkyl, haloalkyl, amido, carbonyl, amido, and heteroaryl.
 22. The method of claim 18, wherein R⁷ is selected from H, alkyl, aralkyl, heteroaralkyl, cycloalkyl, and heterocyclyl.
 23. The method of claim 1, wherein R^(1a) and R^(2a) are each hydroxy.
 24. The method of claim 1, wherein R^(1a) is hydroxy and Rib is H.
 25. The method of claim 4, wherein R^(2a) is hydroxy or C₁₋₆alkyl.
 26. The method of claim 1, wherein R^(2b) is substituted or unsubstituted C₂alkynyl.
 27. The method of claim 1, wherein R^(2a) is Me and R^(2b) is ethynyl.
 28. The method of claim 1, wherein R^(2a) is hydroxy and R^(2b) is ethynyl.
 29. The method of claim 1, wherein R^(2b) is propynyl, butynyl,

or unsubstituted or substituted


30. The method of claim 1, wherein R⁴ is selected from —C(O)OR⁹, —C(O)NR¹¹R¹², —S(O)₂R¹⁰, and —P(O)(OR¹¹)(OR¹²).
 31. The method of claim 30, wherein R⁴ is —C(O)OR⁹ and R⁹ is H or alkyl.
 32. The method of claim 30, wherein R⁴ is —C(O)NR¹¹R¹².
 33. The method of claim 32, wherein each R¹¹ and R¹² is independently selected from H and alkyl; or R¹¹ and R¹², together with the nitrogen atom to which they are attached, form a 5- to 7-membered heterocyclyl.
 34. The method of claim 1, wherein R⁶ is —C(O)OR⁹ and R⁹ is H or alkyl.
 35. The method of claim 1, wherein R⁶ is —C(O)NR¹⁶R¹⁷.
 36. The method of claim 1, wherein R⁴ and R⁶ are each —C(O)OH.
 37. The method of claim 18, wherein R^(a) is selected from H, Cl, —NR⁷R⁸, and phenyl.
 38. The method of claim 1, wherein R⁵ is benzyl.
 39. The method of claim 1, wherein the CD73 inhibitor is selected from any one of the following compounds: Example # Compound 2

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or pharmaceutically acceptable salts and/or prodrugs thereof. 